Design, Synthesis, and Photophysical Properties of Corannulene-Based Organic Molecules

Home , Corannulene

Design, Synthesis, and Photophysical Properties of Corannulene-based Organic Molecules

A Dissertation submitted to the

Graduate School

of the University of Cincinnati

In partial fulfillment of the

requirements for the degree of

DOCTOR OF PHILISOPHY

In the Department of Chemistry

of the McMicken College of Arts and Sciences

Derek R. Jones

B.S. Chemistry

Shawnee State University, June 2006

Committee Chair: Dr. James Mack

November 2011

Abstract

Design, Synthesis, and Photophysical Properties of Corannulene-based Organic Molecules

Derek R. Jones

Since their discovery, fullerenes and nanotubes have spearheaded the development of nanotechnology. However, they are difficult to synthesize and modify for specific tasks.

Corannulene, which is 1/3 of fullerene [60], has unique fluorescent and electrochromic properties that can be applied in a variety of fields. Furthermore, corannulene-based organic materials have the potential to advance organic light emitting diode (OLED) technology.

Corannulene-based organic molecules have been designed and synthesized. Studies have shown a significant red shift in the absorbance spectra and increased luminescence of these molecules compared to the parent structure. Further studies of these corannulene-based materials will help unravel applications suitable for uses in an assortment of nanotechnological fields.

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Acknowledgements

I would never have been able to finish my dissertation without the help, guidance, and support of many different people throughout this exciting (and sometimes difficult) journey of graduate school. First and foremost I want to give thanks and praise to my Lord and Savior,

Jesus Christ, for his strength and guidance through the most difficult of times. With him, all things are possible. I would also like to give my utmost and deepest thanks to my wife,

Amanda, for her unending love and encouragement. Her support and motivation (along with enduring all my practice talks) always gave me the help I needed along the way. She was always there for me, standing by me through thick and thin.

I would also like to express my most sincere gratitude to my advisor, Dr. James Mack, for giving me the opportunity to succeed and providing me with an excellent atmosphere for doing research. His guidance and advice was always welcome. I would also like to thank the

University of Cincinnati, Department of Chemistry for giving me the chance to fulfill my dream of achieving my Ph.D. I would also like to thank my committee members, Dr. Anna

Gudmundsdottir and Dr. Thomas Ridgway for help in guiding my research and proving assistance with my photochemistry and electrochemistry questions. I would also like to give special thanks to Dr. Necati Kaval who was always willing to help and take time out of his day to assist me in using his lasers. I would also like to thank the rest of the faculty and staff in the chemistry department who helped make my dream a reality-- (specifically but not limited to)

Dr. Jeanette Krause (Crystallography), Dr. Elwood Brooks and Dr. Keyang Ding (NMR facility),

Dr. Stephen Macha and Dr. Larry Sallans (Mass Spectrometry), John Salter, Kim Carey, John

Baker, John Zureick, Dr. Deborah Lieberman and Dr. Joel Shulman. Dr's. Lieberman and

Shulman provided great assistance as teaching advisors. Special mention goes to Dr. Shulman for his help and guidance he provided during my job search and preparing me for "life after graduate school."

In addition, I would like to thank all the Mack group members (past and present) for their help along the way. Also, I would like to thank all the undergraduates who I have had the pleasure of working with and mentoring along the way. Thanks also goes out to my fellow chemistry graduate school students, in particular, Upul Ranaweera and Qian Li, for their help in collaborative projects. I would also like to thank Andrew Callender and Dr. Ted Goodson III at the University of Michigan, and Dr. Andreas J. Athans and Dr. Echegoyen at Clemson University for help with collaborative projects as well.

I would also like to thank my parents, my brother, my sister, and all my friends for always supporting and encouraging me in all my endeavors. Their help and assistance was always welcome.

Table of Contents

Chapter Page

1. Introduction

Nanotechnology ...... 1 Fullerenes ...... 1 Nanotubes ...... 6 Corannulene ...... 7

2. Corannulenylethynyl substituted benzenes: Synthesis, structure, and properties

Background ...... 16 Synthesis ...... 20 Results and Discussion ...... 24 Two-photon fluorescence and time-resolved fluorescence ...... 34 Conclusions ...... 38

3. Corannulenylethynyl substituted anthracenes: Synthesis, structure, and properties

Background ...... 40 Synthesis ...... 44 Results and Discussion ...... 51 Conclusions ...... 64

4. Insulating linker: Synthesis, structure, and properties

Background ...... 66 Synthesis ...... 67 Results and Discussion ...... 79 Conclusions ...... 90

5. Substituted pentacenes: Synthesis, structure, and properties

Background ...... 92 Synthesis ...... 94 Results and Discussion ...... 97 Conclusions ...... 102

Chapter Page

6. Photochemical reactions of corannulene

Background ...... 104 Complexation of corannulene with halogen radicals ...... 104 Corannulene-based cis/trans isomerization ...... 105 Synthesis ...... 105 Results and Discussion ...... 107 Complexation of corannulene with halogen radicals ...... 107 Corannulene-based cis/trans isomerization ...... 113 Conclusions ...... 117

7. Experimental methods

Instrumentation and materials ...... 119 Synthetic procedures ...... 120

8. Spectra

Spectra ...... 153

Appendix Page

A. References ...... 245

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List of Figures

Figure Page

Figure 1. Structures of a diamond lattice and graphite ...... 2

Figure 2. Structural relationship of fullerene (C60) and an American soccer ball ...... 3 Figure 3. Graphite electrode arc chamber ...... 4

Figure 4. Geometrical shapes of built onto a 6-6 ring junction of C60 ...... 5 Figure 5. Single-walled nanotube ...... 6

Figure 6. Structural relationship between C60 and corannulene ...... 11 Figure 7. a) Molecular structure of corannulene. b) Electron-density of corannulene c) Curvature of corannulene ...... 12 Figure 8. (1) Absorption spectrum of cyclopentacorannulene and corannulene (2) Fluorescence spectra of cyclopentacorannulene and corannulene ...... 14 Figure 9. Cyclopentacorannulene ...... 15

Figure 10. Absorbance of C60, and ethynyl-linked fullerene ...... 17 Figure 11. Band-gap comparison of corannulene and other aromatic systems ...... 18 Figure 12. Absorption and fluorescence (ex. 300 nm) spectra of corannulene with HOMO and LUMO orbitals ...... 24 Figure 13. Absorption spectra of corannuleylethynyl-benzene series with corannulene and 1,4-bis(phenylethynyl)benzene as comparative standards ...... 25 Figure 14. B3LYP/6-31G* calculated geometries for 11, 12, and 13 ...... 26 Figure 15. HOMO to LUMO and HOMO (-1) to LUMO (+1) transitions for 13 and 11 ...... 29 Figure 16. Fluorescence spectra (excitation 300 nm) ...... 30 Figure 17. Fluorescence spectra (excitation 400 nm) ...... 31 Figure 18. Solutions of corannulene, 11, 12, and 13 excited with 405 nm laser ...... 33 Figure 19. Two-photon excitation ...... 34 Figure 20. Two-photon emission spectra ...... 35 Figure 21. Two-photon cross-section ...... 35 Figure 22. Time-resolved fluorescence, with decay half-lives indicated ...... 36 Figure 23. Transient absorption spectra for 11, 12, and 13 from 100 fs to 100 ps ...... 37 Figure 24. Graphyne ...... 41 Figure 25. Fluorescence emission of selected graphdiyne-based compounds ...... 42

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Figure Page

Figure 26. Commonly used linear acenes ...... 43 Figure 27. Silylethynylated anthracene derivatives ...... 44 Figure 28. Spectra of 9,10-bis(ethynyl)anthracene and decomposition product ...... 47 Figure 29. X-ray crystal structure of 25 ...... 48 Figure 30. Absorption spectra for anthracene (red), 21, 29, 30, 31, and 32 ...... 52 Figure 31. B3LYP/6-31G* calculated geometries for 21, and 30 ...... 55 Figure 32. HOMO to LUMO and HOMO (-1) to LUMO(+1) transitions for 21 and 30 ...... 56 Figure 33. Emission spectra of anthracene ...... 58 Figure 34. Emission spectra of 31 ...... 59 Figure 35. Emission spectra of 30 ...... 60 Figure 36. Emission spectra of 32 ...... 61 Figure 37. Emission spectra of 29 ...... 62 Figure 38. Emission spectra of 21, with isosbestic point at 503 nm ...... 63 Figure 39. Absorbance spectra before and after excitation of 21 at different wavelengths between 400 and 480 nm ...... 64 Figure 40. Proposed structures with ridged insulating linkers ...... 66 Figure 41. GC-MS of compound 42 ...... 70 Figure 42. MALDI-TOF-MS of 33 ...... 71 Figure 43. MALDI-TOF-MS of compound 45 ...... 73 Figure 44. Compound 51 ...... 79 Figure 45. Absorbance spectra of compounds 34, 49, and 50 ...... 79 Figure 46. B3LYP 6-31G* geometry optimized structures of 33 and 34 ...... 81 Figure 47. HOMO to LUMO (+1) and HOMO (-1) to LUMO transitions for 33 ...... 82 Figure 48. HOMO to LUMO (+1) and HOMO (-1) to LUMO transitions for 34 ...... 83 Figure 49. Fluorescence of 34, 49, and 50 with excitation at 405 and 442 nm ...... 84 Figure 50. MALDI-TOF spectrum of compound 51 ...... 85 Figure 51. Absorbance spectra of compounds 34 and 51 ...... 86 Figure 52. B3LYP 6-31G* geometry optimized structures of 51 ...... 87 Figure 53. HOMO, LUMO, HOMO (+1), and LUMO (-1) transitions of 51 ...... 88 Figure 54. Fluorescence spectra of 51 ...... 89 Figure 55. Substituted tetracene and pentacene derivatives ...... 93 Figure 56. Proposed structure of three chromophore compound ...... 94 Figure 57. UV-Vis and fluorescence spectra of corannulene, 1,4-bis(corannulenylethynyl)benzene and unknown coupling product ...... 97

Figure Page

Figure 58. Absorbance spectrum of 52 ...... 98 Figure 59. Fluorescence spectra of 52 ...... 99 Figure 60. B3LYP/6-31G* calculated optimized geometry of three chromophore compound ...... 100 Figure 61. Calculated orbital transitions of three chromophore compound ...... 100 Figure 62. Theoretical UV-Vis spectrum of three chromophore compound ...... 101

Figure 63. Photo-switchable C60 dimer ...... 105 Figure 64. Halogen/corannulene complexes ...... 110 Figure 65. Energy diagram for the singlet and triplet surface of corannulene and 58 ...... 111 Figure 66. Laser flash photolysis of corannulene in argon and oxygen saturated acetonitrile ...... 112 Figure 67. Proposed structure of azo-corannulene for cis-trans isomerization ...... 116 Figure 68. 1H NMR of 2,7-dimethylnaphthalene (2) ...... 153 Figure 69. 13C NMR of 2,7-dimethylnaphthalene (2) ...... 154 Figure 70. 1H NMR of 3,8-dimethylacenaphthenequinone (3) ...... 155 Figure 71. 13C NMR of 3,8-dimethylacenaphthenequinone (3) ...... 156 Figure 72. 1H NMR of 1,6,7,10-tetramethylfluoranthene (4) ...... 157 Figure 73. 13C NMR of 1,6,7,10-tetramethylfluoranthene (4) ...... 158 Figure 74. 1H NMR of 1,6,7,10-tetrakis(dibromomethyl)fluoranthene (5) ...... 159 Figure 75. 13C NMR of 1,6,7,10-tetrakis(dibromomethyl)fluoranthene (5) ...... 160 Figure 76. 1H NMR of corannulene (7) ...... 161 Figure 77. 13C NMR of corannulene (7) ...... 162 Figure 78. 1H NMR of bromocorannulene (8) ...... 163 Figure 79. 13C NMR of bromocorannulene (8) ...... 164 Figure 80. 1H NMR of iodocorannulene (9) ...... 165 Figure 81. 1H NMR of ethynylcorannulene (10) ...... 166 Figure 82. 13C NMR of ethynylcorannulene (10) ...... 167 Figure 83. 1H NMR of 1,2-Bis(corannulenylethynyl)benzene (11) ...... 168 Figure 84. 13C NMR of 1,2-Bis(corannulenylethynyl)benzene (11) ...... 169 Figure 85. MALDI-TOF of 1,2-Bis(corannulenylethynyl)benzene (11) ...... 170 Figure 86. 1H NMR of 1,3- Bis(corannulenylethynyl)benzene (12) ...... 171 Figure 87. 13C NMR of 1,3- Bis(corannulenylethynyl)benzene (12) ...... 172 Figure 88. MALDI-TOF of 1,3- Bis(corannulenylethynyl)benzene (12) ...... 173 Figure 89. 1H NMR of 1,4- Bis(corannulenylethynyl)benzene (13) ...... 174

Figure Page

Figure 90. 13C NMR of 1,4- Bis(corannulenylethynyl)benzene (13) ...... 175 Figure 91. MALDI-TOF of 1,4- Bis(corannulenylethynyl)benzene (13) ...... 176 Figure 92. 1H NMR of (Corannulenylethynyl)benzene (14) ...... 177 Figure 93. 13C NMR of (Corannulenylethynyl)benzene (14) ...... 178 Figure 94. 1H NMR of 2-bromo-(corannulenylethynyl)benzene (15) ...... 179 Figure 95. 13C NMR of 2-bromo-(corannulenylethynyl)benzene (15) ...... 180 Figure 96. 1H NMR of 3-bromo-(corannulenylethynyl)benzene (16) ...... 181 Figure 97. 13C NMR of 3-bromo-(corannulenylethynyl)benzene (16) ...... 182 Figure 98. 1H NMR of 4-bromo-(corannulenylethynyl)benzene (17) ...... 183 Figure 99. 13C NMR of 4-bromo-(corannulenylethynyl)benzene (17) ...... 184 Figure 100. 1H NMR of 2-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (18) ...... 185 Figure 101. 1H NMR of 3-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (19) ...... 186 Figure 102. 1H NMR of 4-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (20) ...... 187 Figure 103. 1H NMR of 9,10-Bis(corannulenylethynyl)anthracene (21) ...... 188 Figure 104. 13C NMR of 9,10-Bis(corannulenylethynyl)anthracene (21) ...... 189 Figure 105. MALDI-TOF of 9,10-Bis(corannulenylethynyl)anthracene (21) ...... 190 Figure 106. 1H NMR of 9,10-bis(trimethylsilylethynyl)anthracene (23) ...... 191 Figure 107. 1H NMR of 9,10-bis(ethynyl)anthracene (24) ...... 192 1 Figure 108. H NMR of trans-Pd(PPh3)2(Cl)(corannulenyl) (25) ...... 193

Figure 109. ESI-MS of trans-Pd(PPh3)2(Cl)(corannulenyl) (25) ...... 194 Figure 110. 1H NMR of 9-bromo-10-formalantharcene (26) ...... 195 Figure 111. 1H NMR of 9-bromo-10-ethynylanthracene (27) ...... 196 Figure 112. 1H NMR of 9-bromo 10-(corannulenylethynyl)anthracene (28) ...... 197 Figure 113. 13C NMR of 9-bromo 10-(corannulenylethynyl)anthracene (28) ...... 198 Figure 114. MALDI-TOF of 9-bromo 10-(corannulenylethynyl)anthracene (28) ...... 199 Figure 115. 1H NMR of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29) ...... 200 Figure 116. 13C NMR of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29) ...... 201 Figure 117. MALDI-TOF of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29) ... 202 Figure 118. 1H NMR of 9-(corannulenylethynyl)anthracene (30) ...... 203 Figure 119. 13C NMR of 9-(corannulenylethynyl)anthracene (30) ...... 204 Figure 120. MALDI-TOF of 9-(corannulenylethynyl)anthracene (30) ...... 205 Figure 121. 1H NMR of 9-(phenylethynyl)anthracene (31) ...... 206 Figure 122. 1H NMR of 9,10-bis(phenylethynyl)anthracene (32) ...... 207

Figure Page

Figure 123. 1H NMR of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene (34) ...... 208 Figure 124. 13C NMR of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene (34) ...... 209 Figure 125. MALDI-TOF of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene (34) ...... 210 Figure 126. 1H NMR of 1,4-dicarbethoxy-2,5-diketobicyclo[2.2.2]octane (35) ...... 211 Figure 127. 1H NMR of diethyl-2,5-bisdithianebicylco[2.2.2]octane-1,4-dicarboxylate (36) ...... 212 Figure 128. 1H NMR of diethyl-bicyclo[2.2.2]octane-1,4-dicarboxylate (37) ...... 213 Figure 129. 1H NMR of bicyclo[2.2.2]octane-1,4-dimethanol (38) ...... 214 Figure 130. 1H NMR of bicyclo[2.2.2]octane-1,4-dicarboxaldehyde (39) ...... 215 Figure 131. 1H NMR of 1,4-bis(2,2-dibromovinyl)bicylo[2.2.2]octane (40) ...... 216 Figure 132. 1H NMR of 1,4-bis(ethynyl)benzobicyclo[2.2.2]octane (41) ...... 217 Figure 133. 1H NMR of 9,10-bis(trimethylsilylethynyl)triptycene (43) ...... 218 Figure 134. 13C NMR of 9,10-bis(trimethylsilylethynyl)triptycene (43) ...... 219 Figure 135. 1H NMR of 9,10-diethynyltriptycene (44) ...... 220 Figure 136. 13C NMR of 9,10-diethynyltriptycene (44) ...... 221 Figure 137. 1H NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene (47) ...... 222 Figure 138. 13C NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene (47) ...... 223 Figure 139. 1H NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)triptycene (48) ...... 224 Figure 140. 13C NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)triptycene (48) ...... 225 Figure 141. 1H NMR of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49) ...... 226 Figure 142. 13C NMR of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49) ...... 227 Figure 143. MALDI-TOF of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49) ...... 228 Figure 144. 1H NMR of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10- (triisoproylsilylethynyl)triptycene (50) ...... 229

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Figure Page

Figure 145. 13C NMR of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10- (triisoproylsilylethynyl)triptycene (50) ...... 230 Figure 146. MALDI-TOF of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10- (triisoproylsilylethynyl)triptycene (50) ...... 231 Figure 147. 1H NMR of 6,13-bis(phenylethynyl)pentacene (52) ...... 232 Figure 148. 1H NMR of 6,13-bis(trimethylsilylethynyl)penta-6,13-diol (53) ...... 233 Figure 149. 1H NMR of 6,13-bis(trimethylsilylethynyl)-6,13-bis(t-butlydimethylsilyl) -pentacene (54) ...... 234 Figure 150. 1H NMR of acetylcorannulene (58) ...... 235 Figure 151. 13C NMR of acetylcorannulene (58) ...... 236 Figure 152. 1H NMR of benzoylcorannulene (59) ...... 237 Figure 153. 13C NMR of benzoylcorannulene (59) ...... 238 Figure 154. 1H NMR of corannulene aldehyde (60) ...... 239 Figure 155. 13C NMR of corannulene aldehyde (60) ...... 240 Figure 156. 1H NMR of 1-corannulenyl-1-propene (61) ...... 241 Figure 157. 13C NMR of 1-corannulenyl-1-propene (61) ...... 242 Figure 158. 1H NMR of 1-corannulenyl-3-phenylpropenone (62) ...... 243 Figure 159. 13C NMR of 1-corannulenyl-3-phenylpropenone (62) ...... 244

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List of Schemes

Scheme Page

Scheme 1. Generic schematic of nucleophilic attack of C60 followed by quenching by electrophile ...... 5 Scheme 2. Barth and Lawton's multi-step synthesis of corannulene ...... 8 Scheme 3. Flash vacuum pyrolysis of corannulene ...... 8 Scheme 4. Solution-based synthesis of corannulene ...... 10 Scheme 5. Formation of pentafluorophenylethynyl-corannulene and bicorannulene acetylene ...... 19 Scheme 6. Original synthesis of di-substituted bis(corannulenylethynyl)benzenes ...... 21 Scheme 7. Synthesis of di-substituted bis(corannulenylethynyl)benzenes ...... 22 Scheme 8. Synthesis of corannulenylethynyl-benzene ...... 22 Scheme 9. Improved synthesis of di-substituted bis(corannulenylethynyl)benzenes ...... 23 Scheme 10. Original synthetic strategy for the synthesis of 21 ...... 45 Scheme 11. Synthetic strategy for the synthesis of 21 ...... 46

Scheme 12. Synthesis of trans-Pd(PPh3)2(Cl)(Corannulenyl) 25 ...... 47 Scheme 13. Improved synthesis of 21 ...... 49 Scheme 14. Synthesis of 29 ...... 50 Scheme 15. Synthesis of 30 ...... 51 Scheme 16. Synthesis of 1,4-bisethynylbicyclo[2.2.2]octane 41 ...... 68 Scheme 17. Synthesis of mono-substituted 1,4-bisethynylbicyclo[2.2.2]octane 42 ...... 69 Scheme 18. Synthesis of 33 ...... 71 Scheme 19. Synthesis of 9,10-bisethynyltriptycene 44 ...... 72 Scheme 20. Synthesis of mono-substituted 9,10-bisethynyltriptycene 45 ...... 73 Scheme 21. Hypothesized intermolecular Diels-Alder reaction of 45 ...... 74 Scheme 22. Synthesis of compound 47 ...... 75 Scheme 23. Synthesis of compound 49 ...... 76 Scheme 24. Synthesis of compound 50 ...... 77 Scheme 25. Synthesis of compound 34 ...... 78 Scheme 26. Synthesis of compound 52 ...... 95 Scheme 27. Proposed synthesis of 57 ...... 96 Scheme 28. Synthesis of acetylcorannulene 58 and benzoylcorannulene 59 ...... 106 Scheme 29. Synthesis of 1-corannulenyl-1-propene 61 and 1-corannulenyl-3-phenylpropenone 62 ...... 107

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Scheme Page

Scheme 30. Photolysis of corannulene with chloroform and bromoform ...... 108 Scheme 31. Photolysis of corannulene with chloroform and bromoform ...... 109 Scheme 32. Photolysis of 61 ...... 113 Scheme 33. Proposed cis-trans isomerization of 61 ...... 114 Scheme 34. Proposed mechanism for the formation of corannulene aldehyde ...... 114 Scheme 35. Energy profile for triple surface for addition of oxygen ...... 115 Scheme 36. Energy profile for singlet surface for addition of oxygen to alkenes ...... 115 Scheme 37. Photolysis of 62 ...... 116

List of Tables

Table Page

Table 1. Calculated TD-DFT wavelength (nm) for most relevant transitions compared to experimental values at B3LYP/6-31G* ...... 28 Table 2. Calculated TD-DFT wavelength (nm) for most relevant transitions compared to experimental values at 6-31G* for 21, 29, and 30 ...... 54

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CHAPTER 1

INTRODUCTION

Nanotechnology

Nanotechnology is a broad term that encompasses a wide range of topics within the scientific world. The idea of nanotechnology was conceived by physicist Richard Feynman at an

American Physical Society meeting in 1959 with the idea that you could manipulate one set of atoms or molecules in order to build and control another proportionally smaller set of atoms or molecules.1 The term nanotechnology was first coined by Professor Norio Taniguchi in a 1974, describing it as “the processing of, separation, consolidation, and deformation of materials by one atom or one molecule.” Nanotechnology got off the ground with the invention of the scanning tunneling microscope in 1981.2 This innovation led to the discovery of fullerenes in

1985 and carbon nanotubes shortly after. Harold Kroto, Robert Curl, and Richard Smalley were awarded the Nobel Prize in Chemistry in 1996 for their discovery of fullerenes. Fullerenes and nanotubes have been at the forefront of the tremendous growth in nanotechnology in the previous twenty years.

Fullerenes

Carbon is the fifteenth most abundant element in the Earth's crust, and the fourth most abundant element in the universe; considerable quantities occur in organic deposits of coal, oil, and gas and are the chemical basis of all known life. Until the twentieth century, only two allotropes of carbon were known--diamond and graphite. Although both are forms of carbon, their physical properties differ greatly. Carbon atoms in diamonds are arranged in a face-

1 centered cubic crystal structure called a diamond lattice and have strong covalent bonds between them, leading to the highest hardness and thermal conductivity of any bulk material.

Diamond is also vastly transparent and is known for its unique optical properties. Graphite is the most stable form of carbon and is an excellent electrical conductor. Graphite is black in color and is most commonly used as "lead" in pencils and as lubricants. Graphite has a layered, planar structure and its unique electrical conductivity is due to the high aromaticity leading to considerable electron delocalization between the carbon layers (Figure 1).

Figure 1. Structures of a diamond lattice and graphite.

Buckminsterfullerene (C60) is a relatively new allotropic form of elemental carbon and is produced during the studies of nucleation in a carbon plasma formed by laser evaporation of

3 graphite. Buckminsterfullerene (C60) was named after Richard Buckminster Fuller, a noted architectural modeler who popularized the geodesic dome. Fullerenes or "buckyballs" exhibits a closed carbon framework with 20 hexagons and 12 pentagons (Figure 2) and resembles an

American soccer ball. Fullerene carbon atoms are sp2 hybridized and form geodesic cages.

Figure 2. Structural relationship of fullerene (C60) and an American soccer ball.

The C60 molecule has two different bond lengths. C-C bonds at 6-6 junctions (between two hexagons) can be considered as double bonds and measure 1.40 Å, whereas C-C bonds at 6-5

4 junctions (between a hexagon and a pentagon) are longer and measure 1.45 Å. Although C60 is the most stable and abundant fullerene, higher fullerenes (i.e. C70, C76, C84) are found as small impurities. In 1990, Kratschmer and Huffman developed a way to synthesize gram quantities of fullerenes by passing a current between two graphite electrodes in an atmosphere of helium

5-6 causing the graphite to vaporize(Figure 3). Presently, C60 is manufactured on a metric ton scale every year.

Figure 3. Graphite electrode arc chamber. (1) motor for anode position control to maintain a constant inter-electrode distance, (2) quartz optical access ports for plasma spectroscopy, (3) anode, (4) cathode, (5) electrode holding platform, (6) glass dumbbell.

Fullerene (C60) has the chemical reactivity similar to that of an electron deficient olefin.

C60 reacts readily with nucleophiles and is a reactive 2p component in cycloadditions. The majority of reactants attack the 6-6 ring junctions of C60, which possess more electron density.

The insertions into 5-6 ring junctions have been reported only as rearrangements following a

6-6 junction attack. Adducts of C60 can be achieved by addition of a nucleophile followed by quenching with an acid or an electrophile (Scheme 1). Usually, a 1,2-addition is observed, with many different adducts possible (Figure 4).7

Scheme 1. Generic schematic of nucleophilic attack of C60 followed by quenching by electrophile.

Figure 4. Geometrical shapes of built onto a 6-6 ring junction of C60.

Since their first detection and bulk production3, fullerenes have played a leading role in the development of nanotechnology. Fullerenes are of great interest in this emerging field because they possess unique structural and electrical properties. Fullerenes unique properties are desirable for various fields—including nanoelectronics and materials science.7 Fullerenes have numerous applications which include incorporation into polymers to obtain electroactive polymers or polymers with optical limiting properties, incorporation into thin films, and the design of novel molecular electronic devices.7 Furthermore, fullerenes have also been used for potential uses in medicine including: enzyme inhibition, photodynamic therapy, and electron

5 transfer.8 Its unusual closed geodesic structure can also be used for the entrapment of molecules.

Nanotubes

Carbon nanotubes are allotropes of carbon and were originally discovered in 1991 by

Sumio Iijima.9 Several techniques have been developed to produce nanotubes in large quantities including arc discharge. Nanotubes were first observed in the carbon soot of graphite electrodes in an attempt to produce fullerenes, similar to the method used by

Kratschmer and Huffman. This method is the most widely used to produce nanotubes with yields of up to 30 percent.10

Nanotubes can be classified as “cylindrical fullerenes” and are usually only a few nanometers wide. Nanotubes can be classified as single-walled nanotubes (SWNTs) or multi- walled nanotubes (MWNTs) (Figure 5).

Figure 5. Single-walled nanotube (SWNT).

Since nanotubes are in the same class of molecules as fullerenes, they posses similar properties and applications. Nanotubes have properties that include high tensile strength, high electrical conductivity, high ductility, high resistance to heat, and relative chemical inactivity. Although fullerenes and nanotubes have the above mentioned unique structural and physical properties, current methods in which they are synthesized make it difficult to modify them chemically for specific tasks. Since their discovery, there have been thousands of publications and patents exploring their unique properties; however, progress towards tailoring them for specific chemical tasks has been slow.11-12 The “difficult processibility1” of fullerenes and complex mixtures prove troublesome for specific application. Furthermore, the inability to consistently reproduce single walled nanotubes is still a major concern. It is these issues that limit the implementation of these molecules into viable uses in nanotechnology.

Corannulene

The advancement of nanotechnology is reliant on the discovery of new and promising materials. The area of fullerene fragments has been around for nearly forty years, but has mostly been overlooked in the field of nanotechnology due to the original lengthy synthesis and small quantities produced. Corannulene, which represents 1/3 of C60, consists of a cyclopentane ring fused with five benzene rings. Corannulene was first synthesized in the

1960's by Barth and Lawton. The original synthesis was long and cumbersome with an overall yield of only 0.4% (Scheme 2).13-14

Scheme 2. Barth and Lawton's multi-step synthesis of corannulene.

Barth and Lawton were able to determine a bowl shaped geometry for corannulene, resulting in unusual strain associated with the central five-member ring. Furthermore, they concluded that all ten hydrogens on the outer rim of corannulene were equivalent resulting in a singlet in the 1H NMR spectrum.

Corannulene research went nearly dormant for over two decades. The original 17 step synthesis hindered any further insight into the chemical behavior of the novel hydrocarbon.

The discovery of fullerenes and nanotubes renewed interest in this unique molecule. In 1991,

Scott and co-workers proposed a three-step synthesis of corannulene using flash vacuum pyrolysis (FVP).15-16

Scheme 3. Flash vacuum pyrolysis of corannulene.

FVP uses high temperatures to deliver enough energy to overcome the high barrier needed for intramolecular ring closures to form the strained curved surface of corannulene The optimal pyrolysis temperature for corannulene was found to be 1000°C and at lower temperatures, only

8 one side was able to be closed.16 However, low yields and the inability to scale up the process has limited the viability of FVP in the synthesis of corannulene. Therefore, it was integral that a solution based model be developed in order to obtain large scale quantities.

Given this, it is of great importance that macroscale quantities of corannulene be produced in order for its unique properties to be fully explored leading to its implementation into the field of nanotechnology. To date, most of the research conducted on corannulene focuses primarily on its synthesis. The Mack group’s synthesis (Scheme 4) of corannulene is based on the foundations of others and allows for the production of multiple gram quantities.17-20

Scheme 4. Solution-based synthesis of corannulene.

Corannulene is of great interest because it has similar properties to that of fullerenes and nanotubes. Corannulene’s structure is similar to C60 in that it maps perfectly onto its surface, shown in Figure 6.

Figure 6. Structural relationship between C60 and corannulene.

Corannulene is one of only a few hydrocarbons to have a strong dipole moment, which is

2.07D.21 In comparison, water has a dipole moment of 1.8D and ammonia that of 1.5D. It also has a curved structure with its electron density localized in the center of the bowl, shown here in Figure 7.

Figure 7. a) Molecular structure of corannulene. b) Electron-density of corannulene c) Curvature of corannulene.

Furthermore, corannulene is one of only a few organic molecules to possess electrochromic properties. Electrochromism refers to the reversible color change associated with a chemical or electrochemical reduction. C60 has a triply degenerate low lying LUMO and has been shown to be electrochemically reduced six times, with reduction potentials of -0.98, -1.37, -1.87, -2.35, -

2.85, -3.26 eV.22 Similarly, corannulene has a doubly degenerate low lying LUMO that can except up to four extra electrons. In 1967, the first two reductions of corannulene were discovered and reported to be 1.88 and 2.36 eV.23 Additionally, they observed noticeable color changes associated with each reduction,. The first reduction gives a green color and the second reduction associated with a bright red species. Attempts at this point to obtain a third and forth reduction were unsuccessful. They also noticed that the oxidations produced a polymeric product that blocked further oxidation. The third and forth reductions were achieved later using lithium wire.24 The third reduction gave a color change to purple, while the

12 fourth reduction gave a brownish color. As to date, the electrochemical reduction potentials of the third and forth reductions are absent from literature since the experiments were observed using NMR.

The overall goal of this dissertation research is to unlock and fine tune the unique properties of corannulene that can be useful in nanotechnological fields. With a better understanding of the properties of corannulene, corannulene-based organic materials can be developed to better tailor them for specific applications. Corannulene has fluorescent properties associated with it, and organic molecules using its framework could have a large impact on a variety of fields, including the display industry.25 It has been observed that the phosphorescence and fluorescence of corannulene has a lifetime of 2.6 ns and 10.3 ns, respectively.26 Corannulene bowl inverts at a rate of approximately 200,000 times per second27, the fluorescence and phosphorescence spectra of corannulene is an average of the continuous bowl inversions (figure 8). The absorption and steady-state fluorescence measurements of corannulene and cyclopentacorannlene were examined to help determine the spectroscopic properties.28

Figure 8. (1) Absorption spectrum of cyclopentacorannulene in cyclohexane. (Inset) Absorption spectrum of corannulene in cyclohexane. (2) Fluorescence spectra of purified samples of (A) cyclopentacorannulene and (B) corannulene. Excitation wavelength = 285 nm.

Cyclopentacorannulene consists of two additional carbon atoms attached to the outer rim of corannulene forming a cyclopentene ring (Figure 9). The additional carbon atoms extend conjugation and increase rigidity and bowl depth to 1.05 Å (corannulene has a bowl depth of

0.89 Å). The observed bathochromic shift from corannulene to cyclopentacorannulene can be attributed to the additional π-electrons that extend the overall conjugation of the corannulene ring system.28 The bathochromic shift of the fluorescence spectrum of cyclopentacorannulene compared to corannulene can also be attributed to the additional π-electrons.

Figure 9. Cyclopentacorannulene.

However, one major drawback to corannulene and cyclopentacorannulene being utilized as fluorescent materials are their low fluorescent quantum yields of (0.07) and (0.01) respectively.28

CHAPTER 2

CORANNULENYLETHYNYL SUBSTITUTED BENZENES: SYNTHESIS, STRUCTURE, AND PROPERTIES

Background

Although corannulene and cyclopentacorannulene suffer from very low quantum yields, the ability to substitute corannulene (and other fullerene fragments) in a manner that keeps the conjugation of the system intact is an important concept to consider. Since all ten hydrogens on the corannulene rim are equivalent, it does not matter where you substituted on the corannulene moiety. The mono-addition of substrates onto the corannulene framework does not disrupt the overall conjugation, allowing the absorbance and fluorescence to be shifted to longer wavelengths. Fullerene absorbs strongly in the ultra-violet region of the electromagnetic spectrum and only slightly in the visible region. Unlike corannulene, linking two fullerene units together with an ethylene bridge breaks the overall conjugation of the system and each fullerene unit act independently from each other (figure 10).29-30 Adding a substituent onto fullerene converts an sp2 hybridized carbon into an sp3 hybridized carbon.

Therefore, no communication between the two fullerenes occurs, with no lowering of the

HOMO-LUMO gap.

Figure 10. Absorbance of C60, and ethynyl-linked fullerene.

Corannulene has a HOMO-LUMO energy gap of approximately 2.3 eV.23 This is advantageous compared to normal polyenes, other aromatic hydrocarbons, and fullerenes. In order for normal-polyenes to achieve an energy gap comparable to corannulene, a large conjugation of atoms is necessary. Since corannulene starts at a lower energy gap, it would take less conjugation to achieve the same results (figure 11).31

Figure 11. Band-gap comparison of corannulene and other aromatic systems.

Siegel and co-workers were able to successfully extend the conjugation of corannulene by adding an ethynyl-moiety to the rim of corannulene. They first brominated corannulene, then added TMS-acetylene through Sonogashira coupling conditions to produce TMS-ethynyl corannulene. Treatment of this compound with potassium fluoride in THF/Methanol produced ethynylcorannulene in good yield (Scheme 5). The π-frame-work of the corannulene alkyne was then elaborated further by coupling the terminal triple bond with a suitable aryl halide.

Ethynylcorannulene was treated with pentafluoroiodobenzene to produce pentafluorophenylethynyl-corannulene and bromocorannulene to produce bicorannulene acetylene (Scheme 5).17

Scheme 5. Formation of pentafluorophenylethynyl-corannulene and bicorannulene acetylene.

Since corannulene has a fluorescence quantum yield of 0.07 in cyclohexane, it can be hypothesized that these new molecules will be considerably more fluorescent than corannulene due to the extended π-conjugation. It was found that the absorbance of pentafluorophenylethynyl-corannulene and bicorannulenyl acetylene was red-shifted when compared to the parent corannulene structure. Both compounds give a pronounced increase in fluorescence quantum yield of 0.26 and 0.57 respectively. Although bicorannulenyl acetylene fluoresces over eight times that of the parent corannulene, it is unstable and decomposes within just a few days even upon refrigeration.17 The fact that corannulene-based organic molecules with extended π-systems can be red-shifted should allow for systems to be designed and synthesized that are robust and stable light emitters for display applications.

Organic light emitting diodes (OLEDs) are advantageous over metal based systems since they

19 are light, cheap and flexible. Furthermore, they consume less power and have faster response times. However, OLEDs have some major drawbacks as well. Primarily, the shorter lifetime of the organic dyes, color-balance issues (blue emitters degrade much fast than red and green), and the efficiency of the blue emitters. Our research group looks to develop and further understand the potential of fullerene fragments as prominent organic-based materials.

Synthesis

Building off the work of Siegel and co-workers, we set out to design robust and stable corannulene-based organic blue light emitters for display applications. Corannulene can be monobrominated by using 3 equivalence of IBr in dry 1,2-dichloroethane in 90% yield to give monobromocorannulene (8). Sonogashira coupling of 8 with TMS-acetylene in the presence of

CuI, diisopropylamine, anhydrous THF and catalytic Pd(PPh3)4 gave TMS-ethynyl corannulene in

97% yield. Deprotection of TMS-ethynyl corannulene with K2CO3 in CH2Cl2 and methanol gave the corresponding ethynyl-corannulene (10) in 94% yield. Ethynyl-corannulene is unstable over long periods of time, and was immediately coupled with 1,2-dibromobenzene, 1,3- dibromobenzene, and 1,4-dibromobenze (Scheme 6). The corresponding di-substituted bis(corannulenylethynyl)benzenes (11-13) were achieved in relatively poor yields (12-15%).

Scheme 6. Original synthesis of di-substituted bis(corannulenylethynyl)benzenes.

In the previous scheme, all unreacted ethynyl-corannulene (10) decomposes, and therefore was not recoverable. Since much time and effort is given to synthesizing corannulene, losing large amounts of ethynylcorannulene is difficult to overcome. Since generally iodine is a better coupling partner than bromine,32-33 monobromocorannulene (8) is converted to monoiodocorannulene (9) by refluxing in the presence of excess CuI and KI in DMF over 48-60 hrs in good yield. 1,2-diiodobenzene, 1,3-diiodobenzene, and 1,4-diiodobenzene are then reacted with TMS-acetylene under Sonogashira coupling conditions. The corresponding di-TMSethynyl benzene is deprotected with K2CO3 in CH2Cl2 and methanol to give the corresponding di-ethynyl benzene compounds. These compounds are then coupled under Sonogashira coupling conditions to give the corresponding di-substituted bis(corannulenylethynyl) (11-13)benzenes in relatively poor yields of 15-18% (Scheme 7). All unreacted iodocorannulene can be recovered after purification and re-used. However, in order

21 to fully understand the potential properties and applications of the interesting molecules, a greater yield needed to be achieved.

Scheme 7. Synthesis of di-substituted bis(corannulenylethynyl)benzenes.

Inspiration to improve the overall yield of synthetic scheme 7 came when 9 was coupled to ethynylbenzene under Sonogashira coupling conditions to give corannulenylethynyl-benzene

(14) in greater than 80% yield (Scheme 8).

Scheme 8. Synthesis of corannulenylethynyl-benzene.

A new step-wise synthetic pathway was then devised to couple on one corannulene at a time.

4-bromo-TMS-ethynyl benzene was converted to ethynyl benzene with K2CO3 in CH2Cl2 and methanol in 98% yield, then coupled to 9 under Sonogashira coupling conditions to give 4- bromo-(corannulenylethynyl) benzene (15) in 80% yield. 15 was then coupled to TMS-

22 acetylene under Sonogashira coupling conditions to give 4-(TMSethynyl)-(corannulenylethynyl) benzene (16) in 90% yield. Deprotection with K2CO3 in CH2Cl2 and methanol followed by coupling with iodocorannulene gave the corresponding 1,4-bis(corannulenylethynyl)benzene

(13) in 60% yield (Scheme 9). The overall yield for these coupling reactions is three times the previous coupling reactions at approximately 42%. 1,2 and 1,3- bis(corannulenylethynyl)benzenes (11-12) are synthesized in the exact same manner by utilizing

2-bromo and 3-bromo-TMS-ethynyl benzene respectively.

Scheme 9. Improved synthesis of di-substituted bis(corannulenylethynyl)benzenes.

Results and Discussion

Corannulene gives two prominent absorption bands centered at 254 nm and 289 nm.

The absorption at 289 nm is the HOMO-LUMO transition and spread across the entire corannulene structure. When excited at 300 nm corannulene fluoresces in the blue region of the electromagnetic spectrum (figure 12).

Figure 12. Absorption and fluorescence (ex. 300 nm) spectra of corannulene with HOMO and LUMO orbitals.

As shown, corannulene does not absorb in the visible part of the electromagnetic spectrum

(400-800 nm). Since adding conjugation to the outer-rim of corannulene has been shown to produce a red-shift in absorbance, we modeled corannulene-based systems with extended π-

-5 frameworks. After purification, 1x10 M CH2Cl2 solutions of 7, 11, 12, 13, and 14 were made

24 and their absorption spectra were recorded (figure 13).34 As a comparison, 1,4- bis(phenylethynyl)benzene (red trace) was synthesized and recorded as well.

0.4

0.35

0.3

0.25

0.2

Absorbance 0.15

0.1

0.05

0 225 265 305 345 385 425 465 505 545 Wavelength

Figure 13. Absorption spectra of corannulenylethynyl-benzene series with corannulene and 1,4-bis(phenylethynyl)benzene as comparative standards.

We can see addition of a phenylethynyl substituent onto the corannulene structure to produce

14, gives two prominent absorption bands centered at 256 nm and 300 nm with a shoulder extending to 395 nm. Two prominent absorption bands were observed for 11 centered at 257 nm and 302 nm with a long tail that trails into the visible region of the spectrum. Compound 12 gives similar results with two prominent absorption bands observed at 259 nm and 302 nm with a long tail that also trails into the visible region of the spectrum. Compound 13 gives three prominent absorptions centered at 256 nm, 307 nm, and 371 nm with a broad shoulder trailing

25 into the visible region of the spectrum. As a comparison, the 1,4-bis(phenylethynyl)benzene gives no absorption in the visible region of the spectrum, and more conjugation would be needed to achieve desirable results. To gain insight into the absorption spectrum we preformed density functional theory (DFT) and time-dependent-density functional theory (TD-

DFT) calculations on the geometry and absorption spectra for 11, 12, and 13. TD-DFT calculations were calculated at the B3LYP level of theory with a 6-31G* bases set(Figure 14).34

Figure 14. B3LYP/6-31G* calculated geometries for 11, 12, and 13.

The B3LYP/6-31G* geometry optimized structure for 11 places the outer rim of one corannulene moiety directly over the interior rim of the other corannulene moiety. This is very similar to the way corannulene behaves in its crystalline form. X-ray crystallographic data of corannulene shows the two corannulene units in a extremely similar arrangement.35 Each bowl

26 is twisted, with a twist angle of approximately 7°, with respect to the central benzene ring.

Compound 12 is connected in such a way through the benzene ring that the two corannulene moieties should have strongly overlapping π -orbitals which would maximize conjugation.

However, the deviation from planarity results in a loss in the overlap of the π-orbitals. This leads to less absorption in the longer wavelength regions of the electromagnetic spectrum (i.e. less red shift).

The B3LYP/6-31G* geometry optimized structure for 12 is calculated to be nearly planar with both corannulene moieties only slightly twisted with respect to the central benzene ring.

Although nearly planer, the two corannulene units are connected in such a way through the benzene ring that no communication should be observed between them. The slight red-shift associated with this molecule can be attributed to the added conjugation of one corannulene through the triple bond and into the benzene ring.

The B3LYP/6-31G* geometry optimized structure for 13 is calculated to be a nearly planar structure with both corannulene moieties twisted less than 1° with respect to the benzene ring. Compound 13 differs from compound 12 because the two corannulene moieties are substituted in a way that should allow for ample communication between the two corannulene units. Furthermore, the fact that compound 13 is nearly planar should allow for maximum overlap of the π-orbitals and allow for the maximum red-shift in the absorbance spectrum. To demonstrate the accuracy of our calculated data, we compared the calculated wavelengths to our experimental wavelengths for the most relevant transitions (table 1).34

Table 1. Calculated TD-DFT wavelength (nm) for most relevant transitions compared to experimental values at B3LYP/6-31G*.

According to TD-DFT calculations, corannulene should have significant transitions at 254 nm and 283 nm. These correlate well with the experimental transitions of 254 nm and 289 nm.

TD-DFT calculations for 11 predict a transition at 293 which correlates nicely with the observed transition at 299 nm. However, calculations for 11 predict the HOMO-LUMO transition to be at

425 nm. This transition is not observed experimentally, and can be attributed to the intramolecular bowl-to-bowl interactions that are not accounted for in the TD-DFT/B3LYP level of theory. TD-DFT calculations for 12 give a significant transition at 300 nm which correlates exactly with the observed transition at 300 nm. TD-DFT calculations for 13 give significant absorption bands centered at 244 nm, 303 nm, and 401 nm. Observed absorption bands for 13 correlate adequately with bands at 250 nm, 302 nm, and 371 nm. Comparison of the TD-DFT calculations at the B3LYP level of theory to the experimental results shows that this level of theory does an acceptable job of predicting relevant transitions. For 13 the HOMO-LUMO

28 transition is undervalued at this level of theory which is consistent with highly conjugated systems.

To give greater insight into the orbital transitions, calculations were performed on compounds 11 and 13 (figure 15). For each given molecule, the HOMO, LUMO, HOMO (-1), and

LUMO (+1) orbitals are shown.

Figure 15. HOMO to LUMO and HOMO (-1) to LUMO (+1) transitions for 13 and 11.

The HOMO to LUMO transition for each of the two compounds goes through the benzene ring and extends into the two corannulene units--showing conjugation throughout the entire molecule. However, as mention previously, 11 deviates from planarity and therefore does not have constructive overlap of the π-system. The HOMO (-1) to LUMO (+1) transition is primarily

29 centered on the two corannulene units and corresponds to the same transition as the HOMO to

LUMO transition on the parent corannulene centered at approximately 300 nm.

From the absorption spectra, we concluded that extending conjugation of the parent corannulene leads to a significant red-shift. This would allow us to hypothesize that the fluorescence spectra of 11, 12, 13 and 14 should also be red-shifted. To determine if this was the case, each of the compounds were excited at 300 nm and 400 nm (Figures 16 & 17).34

300

200 Intensity

100

0 300 400 500 Wavelength

Figure 16. Fluorescence spectra (excitation 300 nm).

1000 900 800 700 600 500 400

Intensity 300 200 100 0 410 460 510 560 Wavelength (nm)

Figure 17. Fluorescence spectra (excitation 400 nm).

The fluorescence spectra of corannulene--when excited at 300 nm--gives one single broad low intensity blue emission centered at 430 nm. All three bis(corannulenylethynyl)benzene structure show a pair of emission bands; the peak emission wavelengths are shifted slightly in the three compounds (418 and 441 nm for ortho, 414 and

434 for meta, 420 and 446 for para). 14 also gives a pair of emission bands centered at 415 and

433 nm. Each corannulenylethynyl compound gives a similar emission spectrum to that of the parent corannulene. It can be concluded that the same transition is being excited in each of the molecules. This can be attributed to the fact that each has a significant transition centered closely to 300 nm that corresponds favorably with the HOMO to LUMO transition shown in figure 11. Although they do not give longer wavelength emissions than that of corannulene, they do give higher fluorescence intensity. Excitation of 11 at 300 nm gives fluorescence

31 intensity (0.08) slightly higher than that of corannulene. 12, 13 and 14 give greatly increased fluorescence intensity (~0.60) when compared to corannulene. The bowl-to-bowl inversion of corannulene is been shown to be on the sub-microsecond time scale.15,36 Since the fluorescence lifetime of aromatic molecules is normally on the nanosecond time scale,37-38 corannulene does not have time to fully invert providing a continuous emission. However, by locking or slowing down the bowl inversion, the two bands can be resolved on the microsecond timescale. Rabideau and co-workers successfully proved this by producing cyclopentacorannulene and locking the bowl.28 The same conclusion can be given for 11, 12,

13, and 14 where adding the ethynyl linkage slows down the bowl inversion and allows for the two bands to be resolved. By comparison 1,4-bis(phenylethynyl)benzene does not have enough conjugation to fluoresce in the visible region of the spectrum--proving that corannulene is essential to be able to absorb in the visible region of the spectrum.

When corannulene is excited at 400 nm (edge of the visible region of electromagnetic spectrum) no emission in observed. Likewise, 1,4-bis(phenylethynyl)benzene gives no fluorescence emission. Compound 11, 12, and 14 all give low fluorescence intensity at this wavelength of excitation. This is to be expected when examining the absorbance of the three compounds (figure 13). Each compound has a long extending tail that only slightly extends into the visible region of the spectrum. As mentioned before, compound 11 has each corannulene unit out of plane from each other, lowering the overall overlap of the π-system. Compound 12 is connected in such a way that no communication should be observed between the two corannulene units. Compound 14 has less conjugation, leading to a smaller red-shift.

Compound 13, however, has both corannulene units planer to the benzene ring and should

32 allow for maximum overlap of the π-system. Compound 13 has a broad shoulder that extends well into the visible region of the spectrum and should absorb well there. When excited at 400 nm, 13 has extremely higher emission with a quantum yield of 0.57.

In contrast to other similar molecules that have been synthesized, and mention previously,17 these compounds are stable to an open atmosphere and have shown no signs of degradation over long periods of time.34 TGA/DSC analysis of the compounds 11 and 13 show no significant changes up to 200° C with only 30% loss of material after ramping to 600°. To determine the viability of these molecules as blue emitters, the compounds were irradiated with a Power Technologies 405 nm, 2 mW laser (figure 18).34

Figure 18. Solutions of corannulene, 11, 12, and 13 excited with 405 nm laser.

Corannulene only gives light scattering with no fluorescence detected. Compounds 11 and 12 give slight blue fluorescence, whereas compound 13 gives intense, bright blue fluorescence.

Two-photon Excited Fluorescence and Time-Resolved Fluorescence39

Two-photon absorption is the concurrent absorption of two photons of identical or differing frequencies in order to excite a molecule from the ground state to a higher energy state (figure 19).40

Figure 19. Two-photon excitation.41

Possible applications for two-photon absorption are imaging, optical limiting power, and 3D optical data storage.42 Compounds 11, 12, and 13 all show emission from two-photon absorption (figure 20).

Figure 20. Two-photon emission spectra of 7 (blue), 11 (green), 12 (red), and 13 (light blue). Intensity normalized relative to maximum value recorded in each spectrum. (Ex 720 nm)

Since two-photon emission has lower spectral resolution, the two bands seen in one- photon emission are not well resolved. Compound 13 shows relatively strong absorption at approximately 680 nm, with a cross-section of 450 GM. The maximum absorption for the 11 and 12 is at a lower wavelength, 670 nm (figure 21).

TPA Cross section

500

450

400 CA mDCA 350 oDCA 300 pDCA

250

200

150 GM (x10^-50 cm^4/sec) (x10^-50 GM 100

0 630 650 670 690 710 730 750 770 790 810 Excitation Wavelength (nm)

Figure 21. Two-photon cross-section of 7 (blue diamond), 11 (pink square), 12 (orange triangle) and 13 (red square).

Compound 13 shows significant absorption about 400 nm in normal steady state measurements (figure 13). However, 13 shows little two-photon absorption in the region of

720-800 nm. This shows that the two-photon absorption excites the same transition in all three compounds. This is consistent with the fluorescence spectra (figure 16), were all corannulene- based compounds excite the same transition and extended conjugation does not lead to red- shift. However, compounds 11, 12, and 13 do show enhanced two-photon cross-section compared to the parent corannulene.

The time-resolved fluorescence emission for 11, 12, and 13 was also conducted.

Compound 13 shows an initial rise time of ~15 ps, followed by a decay with a lifetime of about

120 ps. Compound 11 shows a very fast initial decay, < 5 ps, followed by a slower relaxation of

300 ps. Compound 12 shows only a decay of ~235 ps (figure 22).

Figure 22. Time-resolved fluorescence, with decay half-lives indicated.

The transient absorption spectra of 11, 12, and 13 were conducted and the excited-state spectra of the compounds all differ from that of the parent corannulene. This indicates the excited state is not simply located on the corannulene units (figure 23).

Figure 23. Transient absorption spectra for 11, 12, and 13 from 100 fs to 100 ps.

The transient spectra all show a single broad band in common, centered at ~640 nm for 13,

~570 nm for 12, and ~590 nm for 11. This is the same pattern matching the shifts seen in the fluorescence emission bands. Additionally, 13 shows a sharp band ~740 nm only seen in this isomer. The greater red-shifted band in consistent with a molecule with excitation delocalized over the entire molecule. This molecule is unique given its planarity and connectivity.

Conclusions

Corannulene-based organic materials were designed and synthesized for potential applications in the display industry. Coupling ethynylcorannulene to dibromobenzene led to poor yields and the inability to recover costly corannulene-based materials. Coupling iodocorannulene to diethynylbenzenes gave similar poor yields but allowed for the recovery of corannulene-based compounds. A new step-wise coupling synthetic scheme was devised and allowed not only for the recovery of iodocorannulene, but also tripled the overall yield which should lead to a better understanding of the bulk-scale properties of the target compounds.

The geometry optimized structures of the bis(corannulenylethynyl)benzene series were calculated. Compound 11 shows a deviation from planarity with regard to the benzene.

Compounds 12 and 13 show good planarity, however, 12 is connected in such a way that poor

π- orbital overlap was observed leading to poor communication between the two corannulene units. Orbital calculations of 11 and 13 show HOMO to LUMO transitions through the benzene ring and into both corannulene units.

The optical properties of corannulene and corannulene-based molecules were studied to determine the effect of extended conjugation on the absorption and emission spectra of each. Extending the conjugation of corannulene led to an increase in the wavelength of absorption with 13 have a broad shoulder well into the visible region of the spectrum. The emission spectra, when excited at 300 nm, was the same for each compound to that of the parent corannulene. The same transition was excited, with the inversion of the ethynyl- substituted corannulene units slowed down enough to record two distinct emission bands.

When excited at 400 nm, only 13 gave strong, intense blue fluorescence with high quantum yield. Each of the compounds are stable (even at high temperatures) in open atmosphere and over long periods of time. When excited with a 405 nm laser, 13 gave bright blue fluorescence.

Two photon emission for 13 shows greatly enhanced cross-section relative to corannulene. Compounds 11 and 12 only show slight enhancement. The transient absorption measurements suggest the excited state is delocalized throughout the entire molecule, and not simply on the corannulene units. Compound 13 shows unique behavior, due to its planarity and connectivity. The time-resolved measurements suggest a rapid rearrangement not seen in compound 11 and to a small extent in compound 12. This is consistent with the idea of a fast process involving emission with rapid intersystem crossing to a triplet.

CHAPTER 3

CORANNULENYLETHYNYL SUBSTITUTED ANTHRACENES: SYNTHESIS, STRUCTURE, AND PROPERTIES

Background

For OLED displays, three primary colors need to be produced--blue, green, and red.

Building off our success with corannulene-based organic blue emitting molecules, we set out with two goals:

1) Produce a corannulene-based compound that emits green light and,

2) Produce a corannulene-based compound that emits both blue and green light,

depending on the wavelength of excitation.

In order for green light to be emitted, larger conjugated systems need to be utilized. Graphyne, is a theoretical structure, based off graphite. Substituting one-third of the carbon bonds of graphite with ethyne units, results in the formation of a graphyne composed entirely of phenyl rings and triple bonds (figure 24).43 Graphyne is predicted to have strong nonlinear optical behavior and be considered a semiconductor with a band gap of 1.2 eV.44 However, synthetic accessibility has been the primary deterrent to graphyne-research.

Figure 24. Graphyne.

Haley and co-workers have based their research off this unique structure, and produced graphdiyne-based structures. These structures are large conjugated systems consisting entirely of diynes and phenyl rings. They have shown the ability to fine tune their structures to emit a variety of colors.45-46 By using strategically placed electron-donating and electron-withdrawing substituents on the frameworks, they were able to successfully fine tune the optical emitting properties (figure 25).46

Figure 25. Fluorescence emission of selected graphdiyne-based compounds.

Another robust and versatile platform for the development of functional materials for electronic applications are linear acenes. Linear acenes are poly-aromatic hydrocarbons (PAHs) consisting of fused benzene rings. Commercially, PAHs are obtained from the refining of coal- tar. Commonly used linear acenes are: naphthalene (a white crystalline solid with two fused benzene rings), anthracene (a white crystalline solid with three fused benzene rings), tetracene

(a pale orange power with four fused benzene rings), and pentacene (a purple powder with five fused benzene rings) (Figure 26).

Figure 26. Commonly used linear acenes.

Larger linear acenes are organic semi-conductors and are commonly used as OLED materials.47-

49 John Anthony and co-workers have successfully functionalized linear acenes to emit a variety of colors. For OLEDs, there is a constant need for new and promising materials to emit blue, green, and red. Functionalizing anthracenes in the 9,10-positions leads to green emission.

However, linear acenes are limited by a number of issues. First, acenes larger than anthracene suffer from low solubility and in many cases poor stability. For example, anthracene and larger linear acenes absorb UV light, making them susceptible to oxidation. Larger acenes slowly degrade upon exposure to air and light. Anthony and co-workers functionalized anthracene in both the 9,10- and 1,4- substituted positions (figure 27).47

Figure 27. Silylethynylated anthracene derivatives.

These anthracene derivatives are air stable and soluble in most organic solvents. The compounds were incorporated into OLED devices and showed an emission wavelength of 477 nm. Incorporation of electron donating methoxy groups onto the 9,10- substituted structure in the 2,6 position gave a further red-shift and showed an emission wavelength of 503 nm.

Since novel blue emitters were synthesized based on corannulene, with significant red- shifts in the absorbance spectra, we wanted to synthesize similar structures based on the linear acene, anthracene, that would emit green fluorescence. Our hypothesis is that anthracene will afford us new and exciting fluorescent properties not observed in previous studies.

Synthesis

A similar approach was taken to synthesize the anthracene-based corannulenylethynyl series as was employed in the synthesis of 11, 12, 13, and 14. Originally, ethynylcorannulene

(10) was coupled to 9,10-dibromoanthracene in an attempt to synthesize 9,10- bis(corannulenylethynyl)anthracene (21) (scheme 10).

Scheme 10. Original synthetic strategy for the synthesis of 21.

Unfortunately, this synthetic route did not afford us our desired product. The instability of 10 under the harsh conditions of the Sonogashira coupling reaction (i.e. high temperatures) needed to perform the coupling, led to its degradation. The solubility of 9,10- dibromoanthracene could also have limited our success in this synthetic route. Unsuccessful attempts were made in converting 9,10-dibromoanthracene to the better coupling partner

9,10-diiodoanthracene. Reacting the same compounds at room temperature afforded us only starting materials.

Alternatively, attempts were made to synthesize 21, by coupling iodocorannulene (9) to

9,10-bis(ethynyl)anthracene (scheme 11). Anthracenequinone was converted to 9,10- bis(trimethylsilyl)anthracene (23) be treating TMS-acetylene with n-BuLi in THF then added in the quinone to form diol 22. Dehydration of 22 with SnCl2·2 H2O in 50% aqueous acetic acid gave 23 in 46% yield. 23 was then deprotected with K2CO3 in CH2Cl2 and methanol to afford

9,10-bis(ethynyl)anthracene (24) in 93% yield.

Scheme 11. Synthetic strategy for the synthesis of 21.

This synthetic route was devised to be able to recover unreacted iodocorannulene after purification. However, attempts to synthesize 21 were unsuccessful during the final coupling reaction. At elevated temperatures, 9,10-bis(ethynyl)anthracene (24) was unstable and reacted upon itself in what is presumed to be some sort of Diels-Alder type reaction (Figure 28).

Figure 28. Spectra of 9,10-bis(ethynyl)anthracene and decomposition product.

At lower temperatures, the Diels-Alder reaction did not occur, but we obtained a high yield of trans-Pd(PPh3)2(Cl)(corannulenyl) (25) (scheme 12).

Scheme 12. Synthesis of trans-Pd(PPh3)2(Cl)(Corannulenyl) (25).

Sharp and Siegel have reported similar complexes with platinum and nickel, but to the best of our knowledge, this is the first palladium complex of its type.50-51 This structure is an intermediate of the Sonogashira coupling reaction in which the metal inserts itself between the aromatic compound and the halogen. Since iodocorannulene was used in this reaction, it was

47 assumed that in the intermediate, the palladium would be inserted between the aromatic compound (corannulene) and halogen (iodine). Somewhat surprisingly, upon determination of the X-ray crystal structure, chlorine was the other substituent off palladium and not the original iodine (figure 29). This can be accounted for in the work-up of the reaction with concentrated hydrochloric acid in which the chlorine replaces the iodine.

Figure 29. X-ray crystal structure of 25.

We were able to successfully synthesize compound 25 in good yield, by reacting iodocorannulene, Pd(PPh3)4, and anhydrous THF in a sealable reaction vessel at room temperature for 24 h.

We ultimately synthesized the desired product by reacting 9,10 dibromoanthracene with one equivalent of n-butyllithum followed by dimethylformamide to give 9-bromo-10- formylanthracene (26) in 61% yield; subsequent Corey-Fuchs reaction gave the 9-bromo-10- ethynylanthracene (27) in 71% yield. Coupling 27 to iodocorannulene gave the 9-bromo-10-

(corannulenylethynyl)anthracene (28) in 50% yield. Sonogashira coupling of

48 ethynylcorannulene (10) to 28 gave the desired 9,10-bis(corannulenylethynyl)anthracene (21) in 15% yield (Scheme 13).

Scheme 13. Improved synthesis of 21.

TMS-acetylene was coupled to 28, to afford 9-(trimethylsilylethynyl)-10-

(corannulenylethynyl)anthracene, then deprotected with K2CO3 in methanol and CH2Cl2. The attempt was made to couple the deprotected compound to iodocorannulene, but no product was observed. Although compound 10 is unstable, it was used in the synthetic route since it was theorized the coupling reaction would take place before degradation would occur. The new step-wise synthetic route allowed us new opportunities to make un-symmetrical corannulenylethynylanthracene compounds. Coupling any terminal alkyne to 28 would allow

49 for a variety of molecules. For comparison purposes, we synthesized 9-(ethynylphenyl)-10-

(corannulenylethynyl)anthracene (29) by coupling 28 with phenyl-acetylene in 40% yield

(scheme 14).

Scheme 14. Synthesis of 29.

Additionally, we also synthesized 9-(corannulenylethynyl)anthracene 30 (scheme 15), 9-

(ethynylphenyl)anthracene (31), and 9,10-bis(ethynylphenyl)anthracene (32) for comparative purposes. Compound 30 was synthesized under Sonogashira coupling conditions between 9- ethynylanthracene and iodocorannulene in 63% yield.

Scheme 15. Synthesis of 30.

Results and Discussion

Upon purification of compounds 21, 29, 30, 31, 32 and anthracene, 1x10-5 M solutions of each were made and their absorption spectra were recorded (figure 30). Since we previously concluded that extending the conjugation of corannulene-based systems would lead to a significant red-shift in the absorption spectrum, we presumed compounds 21, 29, and 30 would have an even greater red-shift with possible absorption in the green region of the electromagnetic spectrum (~500-600 nm).

Figure 30. Absorption spectra for anthracene (red), 21, 29, 30, 31, and 32.

Anthracene gives four prominent absorption bands at 328, 343, 359, and 379 nm. It does not absorb in the visible region of the spectrum. 9-(ethynylphenyl)anthracene (31), gives absorbance bands at 402 and 424 nm. 9,10-bis(ethynylphenyl)anthracene (32), gives absorption bands at 442 and 469 nm. From this data, we can conclude that the addition of one ethynylphenyl unit shifts the maximum wavelength of absorption from 379 nm to 424 nm, a difference of 45 nm. Addition of a second ethynylphenyl unit to the 10 position of anthracene, shifts the maximum wavelength of absorbance an additional 45 nanometers to 469 nm. 9-

(corannulenylethynyl)anthracene (30), gives absorption bands at 424 and 449 nm. 9,10-

52 bis(corannulenylethynyl)anthracene (21) gives absorbance bands at 479 and 509 nm. From the absorbance spectra, we can conclude the addition of a corannulenylethynyl substituent to the 9 position of anthracene shifts the maximum wavelength of absorption 70 nanometers, 25 more nanometers more red-shifted than was observed for the addition of phenylethynyl. Addition of a second corannulenylethynyl substituent to the 10 position of anthracene shifts the maximum wavelength of absorption to 509 nm; 40 nanometers more than that of 9,10- bis(phenyletheynyl)anthracene. 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29), gives absorption bands at 461 and 489 nm. Comparison of 29, with 9,10- bis(phenylethynyl)anthracene (32), we conclude that substituting a corannulenylethynyl substituent for a phenylethynyl substituent leads to red-shift of 20 nm. This follows the conclusion that the more conjugation that is present through the central ring of anthracene, the more red-shift in absorbance is observed.

To gain further insight into the absorption spectra of target compounds 21, 29, and 30, we performed density functional theory (DFT) and time-dependent-density functional theory

(TD-DFT) calculations. We employed the B3LYP exchange-correlation functional with a 6-31G* basis set, as implemented in the Gaussian 03 suite of programs.52 It has been shown that B3LYP theory with 6-31G* basis set accurately reproduces bond lengths, bond angles, and dihedral angles for corannulene, therefore should give us accurate geometrical outputs.53 Furthermore, we previously achieved good correlation with experimental results at this level of theory.34

Calculated wavelengths and oscillator frequencies (f) are listed in table 2.

Table 2. Calculated TD-DFT wavelength (nm) for most relevant transitions compared to experimental values at 6-31G* for 21, 29, and 30.

TD-DFT calculations of 30 predicts significant absorption bands centered at 472 (f = 0.5975) and

287 nm (f = 0.3531). TD-DFT calculations for 29 predict the HOMO-LUMO transition to be at

532 nm (f = 1.132), and a second major transition at 291 nm (f = 3.113). Calculations for 21 give predicted transitions at 558 (f = 1.4265), 375 (f = 0.1456), and 295 nm (f = 1.928). Comparing our TD-DFT calculations with the observed absorption spectra, we see an overestimate of the energy levels. Similar reports have shown TD-DFT calculations to overestimate the energy levels of highly conjugated systems.54 Although the absolute values were overestimated, the difference in the calculated maximum absorbance fits with the differences observed in the experimental values. For example, TD-DFT theory predicts the difference in maximum wavelength between 29 and 21 to be 25 nm, experimentally we observe this difference as 20 nm.

The B3LYP/6-31G* geometry optimized structures for 21, 29, and 30 were obtained

(figure 31). All molecules were twisted slightly from planarity due to the close proximity of the corannulenyl hydrogen atoms on the ring with those of the hydrogen atoms on anthracene.

Figure 31. B3LYP/6-31G* calculated geometries for 21, and 30.

The B3LYP/6-31G* geometry optimized structure 30 shows the corannulenyl unit twisted 32° with regard to the anthracene. This twist angle can be clearly seen when observing compound 30 from the side. The B3LYP/6-31G* geometry optimized structure 21 shows a much smaller twist angle with regard to the central anthracene. Compound 21 optimized structure looks nearly planar with distinct similarity to that of 1,4- bis(corannulenylethynyl)benzene (13) which is twisted less than 1° with respect to the benzene ring.

To give greater insight into the orbital transitions, calculations were performed on 21 and 30 (figure 32).

Figure 32. HOMO to LUMO and HOMO (-1) to LUMO(+1) transitions for 21 and 30.

With the ultimate goal of achieving fluorescence in two dimensions, the orbitals of corannulene-based compounds that could emit both blue and green light depending on the wavelength of excitation were studied. The HOMO to LUMO transition for compounds 21 and

30 are both positioned almost entirely on the anthracene ring system. However, we do see some "bleeding" through the triple-bond linkage and into the corannulenyl unit and

56 corresponds the observed transitions at 449 nm for 30 and 509 nm for 21 respectively. The

HOMO(-1) to LUMO (+1) transition for compound 30 is positioned on the corannulenyl unit and corresponds to the 299 nm observed transition. This is the same orbital transition that seen as the HOMO to LUMO transition for the parent corannulene (289 nm). The HOMO(-1) to LUMO

(+1) transition for compound 21 is positioned on the corannulenyl units and appears to go through the central ring of the central anthracene. The orbital transition corresponds to the observed transition seen at 362 nm. Compound 21 has two transitions that should correspond to absorbencies in the visible region of the spectrum, with the 509 nm falling in the green region and the other in the blue region. However, we see that some mixing of these orbitals may occur.

To determine the significance of the orbital transition calculations, and if multiple emissions were possible, we analyzed the emission spectra of 21, 29, and 30. To get a complete all-inclusive outlook of the various factors that affect fluorescence, we also examined the fluorescence of anthracene, corannulene (7), 9,10-bis(phenylethynyl)anthracene (32), and 9-

(phenylethynyl)anthracene (31). Excitation of corannulene (7) at 300 nm has been shown previously (figure 16) gives low intensity blue fluorescence with two emission bands centered at

420 nm and 440 nm. No fluorescence is seen for corannulene when excited at 400 nm (figure

17). Anthracene, when excited at 300 nm, gives emission bands at 381, 402, 425, and 448 nm.

Like corannulene, no fluorescence is seen when exited at 400 nm and is shown to give only light scattering when excited with 405 nm and 488 nm lasers (figure 33).

Figure 33. Emission spectra of anthracene.

9-(phenylethynyl)anthracene (31) when excited at 300, 377, and 400 nm gives two emission bands centered at 428 and 453 nm (figure 34). As expected from examining the absorption spectrum of 31, no significant emission bands should be seen when exciting above

442 nm. Excitation with a 405 nm laser shows bright, blue fluorescence (ca. φ=0.78)55, whereas excitation with a 488 nm laser shows only light scattering.

Figure 34. Emission spectra of 31.

By comparison to 9-(phenylethynyl)anthracene (31), 9-(corannulenylethynyl)anthracene

(30) give emission bands centered at 462 and 480 nm when excited at 300, 400, and 450 nm

(figure 35). These emission bands for 30 are red-shifted by ~30 nm when compared to 31, which is expected since it has been shown that a corannulenylethynyl unit red-shifts the absorbance spectra 20 nm more than a phenylethynyl unit. When excited at 487 nm, only slight emission is observed. Excitation with a 405 nm laser shows bright, blue fluorescence (ca.

φ=0.52)55 similar to that of 31. However, excitation with a 488 nm laser, shows mostly light scattering, with a hint of blue/green fluorescence.

Figure 35. Emission spectra of 30.

9,10-bis(phenylethynyl)anthracene (32) when excited at 300, 400, 450 and 487 nm gives two emission bands centered at 475 and 503 nm (φ=1.00)55 (figure 36). Excitation with 405 and

488 nm lasers gives the same intense blue emission, and seems to follow Kasha's rule. Kasha's rule states that emission is independent from excitation.56 That is, photon emission occurs in acceptable yield only from the lowest excited state of a given multiplicity.

Figure 36. Emission spectra of 32.

9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29) gives two emission bands centered at 498 and 528 nm when excited at 300, 377, 400, 450, and 487 nm (φ=0.88) (figure

37). The substitution of a corannulenylethynyl unit for a phenylethynyl unit gives a red-shift in the emission of spectra of ~25 nm when comparing 29 to 32. Upon excitation with 405 and 488 nm lasers, 29 gives intense green emission also following Kasha's rule. The difference between compounds 29 and 32 is a corannulenylethynyl substituent in place of a phenylethynyl substituent is compound 32 gives a strong blue fluorescence whereas compound 29 give a strong green fluorescence.

Figure 37. Emission spectra of 29.

The most intriguing molecule in this series is 9,10-bis(corannulenylethynyl)anthracene

(21). Unlike the previous molecules in this study, the emission is dependent on the wavelength of excitation. Therefore, it seems to violate Kasha's rule. When excited from 400-480 nm in increments of 10 nm, three emission bands are observed at 460, 518, and 550 nm (ca.φ=0.41)

(figure 38). Upon increasing wavelength of excitation, the emission band at 460 nm decreases, whereas the emission bands at 518 and 550 nm increase. An isosbestic point is observed, occurring at 503 nm. An isosbestic point is a specific wavelength at which two chemical species have the same molar absorptivity (ε). More generally, it is at the wavelength where the spectra cross each other. Excitation with a 405 nm laser gives bluish/green fluorescence, whereas excitation with a 488 nm laser gives intense green fluorescence.

Figure 38. Emission spectra of 21, with isosbestic point at 503 nm.

To gain further insight into these promising results, more detailed experiments were performed to increase our understanding of this unique system. It was hypothesized that the emission between 410-500 nm was the result of a photo-product formed after excitation of compound

21. To determine if this were the case, 21 was excited, left in the dark for 1 hr, then excited again. Absorbance and fluorescence spectra were recorded before and after to determine if any changes would occur (figure 39). It was determined that the spectra before and after where exactly the same, confirming that no photo-product is formed.

Figure 39. Absorbance spectra before and after excitation of 21 at different wavelengths between 400 and 480 nm.

Conclusions

A series of corannulenylethynyl substituted anthracene based molecules were designed and synthesized for potential uses in display applications. Attempts to synthesize 21 by coupling 9,10-bis(ethynyl)anthracene to iodocorannulene (scheme 11) at elevated temperatures led to the degradation of starting materials. Coupling at lower temperatures gave high yields of trans-Pd(PPh3)2(Cl)(corannulenyl) (25) (scheme 12). Building off the success of the step-wise synthetic scheme of the corannulenylethynyl benzene series, a step-wise synthetic scheme to synthesize 21 was constructed (scheme 13). An overall yield of 15% for the final coupling of ethynylcorannulene to 9-bromo-10-(corannulenylethynyl)anthracene (28) allowed for the study of the unique photophysical properties of this series and the development of unsymmetrical substituted anthracene based systems.

The absorbance spectra of the corannulenylethynyl substituted anthracene series was studied and was determined that a phenylethynyl substituent led to an overall red-shift of 45 nm. The addition of a corannulenylethynyl substituent leads to an overall red-shift of 70 nm, an additional 25 nm more red-shifted than the phenylethynyl unit. The overall red-shift of 9,10- bis(corannulenylethynyl)anthracene 21 was 40 nm more than that of 9,10- bis(phenylethynyl)anthracene 32. Additionally, it has been shown that 9-

(corannulenylethynyl)anthracene (30) gave bright blue intense light, whereas, the addition of a phenylethynyl substituent in the position increased the overall conjugation through the central anthracene unit and gave bright green fluorescence. Both compounds are shown to follow

Kasha's Rule. 9,10-bis(corannulenylethynyl)anthracene 21 gave bluish/green fluorescence when excited at 405 nm and green fluorescence when excited at 488 nm. It was determined that this was not the result of a photo-product and that 21 violated Kasha's Rule. The ability of compound 21 to emit different wavelengths of light at different excitation wavelengths shows it viability as a candidate in displays and non-linear optics.

TD-DFT calculations at the B3LYP level of theory using a 6-31G* basis set over estimates the maximum wavelength of absorption which is also seen in other highly conjugated systems.

Calculated orbitals at this same level of theory show the HOMO to LUMO transition of 21 and

30 to be positioned almost entirely on the central anthracene unit with same "bleeding" into the corannulenylethynyl units. The HOMO (-1) to LUMO (+1) transition for 21 and 30 is positioned almost entirely on the corannulenylethynyl unit. Geometry optimized structures of

29 and 30 show nearly planar structures that should lead to maximum overlap of the π- framework.

CHAPTER 4

INSULATING LINKER: SYNTHESIS, STRUCTURE, AND PROPERTIES

Background

We can see from the orbital transitions and the position of the HOMO to LUMO transitions on compound 21, that each orbital is not positioned entirely on the central anthracene ring. Therefore, a system was devised that allowed for a ridged insulating "linker" to be placed between the two chromophores (figure 40).

Figure 40. Proposed structures with ridged insulating linkers.

It has been shown that substituting a corannulenylethynyl unit onto a benzene ring with added conjugation in the para position (compound 11), leads to planar, highly conjugated

66 system with blue emission. It also has been shown that extending the conjugation of anthracene through the central ring, leads to red-shift in the absorbance and green fluorescence (compounds 21 and 30). Therefore, placing a bicyclo[2.2.2]octane unit (33) or a triptycene unit (34) between the two chromophores, should allow us to achieve both blue and green fluorescence without mixing. Additionally, the rigidity of the linker will minimize the loss of energy through vibration.

Synthesis

1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynylbicylco[2.2.2]octane (33) was synthesized through the intermediate 1,4-bisethynylbicyclo[2.2.2]octane (41) (scheme 16).57-61

Diethylsuccinate was treated with 2 equivalence of NaH in anhydrous DME and allowed to stir for 24 hrs. The resulting di-sodium salt was then dissolved in anhydrous DME and dry 1,2- dibromoethane and allowed to stir for 7 days. The product was reacted with 1,2-ethanedithiol in the presence of p-toluenesulfonic acid using a Dean-Stark trap to produce the corresponding bisdithiane (36) in 50-60%. Removal of the thiane groups with Raney nickel gave the diester

(37) in excellent yield (99%). Reduction of 37 with DIBAL-H at room temperature gave the diol

60 (38) in 97% yield. Reduction of 37 with LiAlH4, as reported in the literature, resulted in the recovery of starting material. Reduction of 37 with DIBAL-H at -78° C gave a complex mixture of products (including starting material 37, diol 38, and the monoaldehyde). Oxidation of 38 with

PCC gave the dialdehyde (39) in excellent yield (95%). 1,4-bisethynylbicyclo[2.2.2]octane (41) was produced using Corey-Fuchs reaction through the dibromovinyl (40) intermediate in 58% yield.

Scheme 16. Synthesis of 1,4-bisethynylbicyclo[2.2.2]octane (41).

Wasielewski and co-workers devised a synthetic route to produce unsymmetrical 1,4- bisethynyl[2.2.2]octanes.61 Using 1,4-bisethynylbicyclo[2.2.2]octane (41), they optimized the conditions of mono-addition, using Sonogashira coupling, by reacting 41 to aryl halides for short periods of time (i.e. 15 min). They reported the coupling of 9-bromo-10-cyanoanthracene frequently resulted in only the formation of the disubstituted product. Using these results as a guide, I attempted the coupling of 9-bromoanthracene to 41 for 30 min. After completion, only starting materials were obtained. As to be expected, coupling for longer time periods resulted in the disubstituted product. Knowing that aryl iodo compounds are better coupling partners,

9-bromoanthracene was converted to 9-iodoanthracene is the same fashion that bromocorannulene (8) was converted to iodocorannulene (9). Coupling of 9-iodoanthracene to 41 for 30 min, gave the desired mono-substituted adduct (scheme 17) as confirmed by GC-

MS (figure 41).

Scheme 17. Synthesis of mono-substituted 1,4-bisethynylbicyclo[2.2.2]octane (42).

Figure 41. GC-MS of compound 42.

Reaction of 42 with 4-bromo-1-(corannulenylethynyl)benzene (17) using Sonogashira coupling techniques resulted in the formation of the desired product (33) (scheme 18) as confirmed by

MALDI-TOF-MS (figure 42).

Scheme 18. Synthesis of 33.

Figure 42. MALDI-TOF-MS of 33.

Although compound 33 was able to synthesized, only a small amount was obtained. The coupling of 41 to obtain the mono-substituted product 42 was a very inefficient reaction (20-

25%). The subsequent coupling reaction to produce 33 as the final product occurred in less than 10% giving 8 milligrams.. Therefore, the amount of material was not sufficient for the ensuing photophysical experiments that needed to be completed. Since the synthesis of 1,4- bisethynylbicyclo[2.2.2]octane 41 (scheme 16) was long and costly and with the synthetic ease of producing substituted anthracenes, compound 34 (triptycene linker) was considered. 9,10- bis(trimethylsilylethynyl)anthracene was treated with isoamylnitrite and anthranilic acid to execute a Diels-Alder reaction on the central ring of anthracene. The following deprotection of the TMS group using K2CO3 in MeOH and CH2Cl2 gave the corresponding 9,10- bisethynyltriptycene (scheme 19).61

Scheme 19. Synthesis of 9,10-bisethynyltriptycene (44).

Coupling of 9-iodoanthracene to 44 for 30 min, gave the desired mono-substituted adduct

(scheme 20) as confirmed by MALDI-TOF-MS (figure 43).

Scheme 20. Synthesis of mono-substituted 9,10-bisethynyltriptycene (45).

Figure 43. MALDI-TOF-MS of compound 45.

Subsequent coupling of 4-bromo-1-(corannulenylethynyl)benzene (17) to 45 at higher temperatures led to the degradation of the starting material. It is hypothesized that the terminal alkyne on 45 does an intermolecular Diels-Alder type reaction on the central ring of anthracene on a different molecule of 45. Coupling of 17 to 45 at lower temperatures returned the corresponding starting materials. Therefore, this is not a successful route in obtaining the target molecule (34) (Scheme 21).

Scheme 21. Hypothesized intermolecular Diels-Alder reaction of 45.

In order to produce the unsymmetrical triptycene needed for the final product, an unsymmetrical anthracene starting material was needed. Using stoichiometry in our favor, we used equal molar amounts of TMS-acetylene and TIPS-acetylene in the formation of 9-

(trimethylsilylethynyl)-10-(triisopropylsilyethynyl)anthracene (47). Stoichiometry predicts that

50% of the final product should be the unsymmetrical desired product with 9,10- bis(trimethylsilylethynyl)anthracene and 9,10-bis(triisopropylsilylethynyl)anthracene comprising of 25% each. Treating the 1:1 mixture of TMS-acetylene and TIPS-acetylene in anhydrous THF with 1.9 equivalents of n-BuLi, followed by the addition of anthracenequinone gave the mixture of diols (46). Subsequent dehydration using SnCl2 ·H2O in 50% aqueous acetic acid gave the corresponding mixture of 9,10-substituted anthracenes (scheme 22). Separation by column chromatography (~1 mL/min elution) gave the desired product (47) as ~40% of the mixture.

Scheme 22. Synthesis of compound 47.

Treating 47 with isoamylnitrite and anthranilic acid (produces benzyne intermediate) executed a Diels-Alder reaction on the central ring of anthracene giving 9-(trimethylsilylethynyl)-10-

(triisopropylsilyethynyl)triptycene (48) in 25% yield. Selective deprotection of the TMS group with K2CO3 in methanol and CH2Cl2 with subsequent coupling of 9-iodoanthracene gave the 9-

(anthracenylethynyl)-10-(triisopropylethynyl)triptycene (49) in 20% yield (scheme 23). Coupling

4-bromo-1-(corannulenylethynyl)benzene after selective deprotection gave 9-[4-

(corannulenylethynyl)]-10-(triisopropylethynyl)triptycene (50) in 50% yield (scheme 24).

Scheme 23. Synthesis of compound 49.

Since the deprotection of 49 will give product 45 (scheme 20) and compound 45 is not useful in the next coupling step, this synthetic route was abandoned. Compound 49 will only be

76 used in the photophysical (absorption, fluorescence, emittance) studies as a standard of comparison.

Scheme 24. Synthesis of compound 50.

The formation of compound 50 allows us to complete the synthetic route and achieve are target compound (34). Deprotection of 50 with TBAF in THF, followed by Sonogashira coupling of 9-iodoanthracene to terminal alkyne gave the target compound (34) in 22% yield

(scheme 25). In addition, a small amount of 50 was held to use in the photophysical experiments as a standard of comparison.

Scheme 25. Synthesis of compound 34.

The photophysical properties of 34 was compared with the photophysical properties of

49 and 50. In addition to compound 50, an additional compound with even greater conjugation through the central ring on anthracene was attempted. Deprotection of 50 with TBAF in THF, followed by Sonogashira coupling of 9-bromo-10-(corannulenylethynyl)anthracene (28) attempted to make 9-[9-(corannulenylethynyl)-10-ethynyl]-10-[4-(corannulenylethynyl)-1- ethynyl]triptycene (51) (figure 44).

Figure 44. Compound 51.

Results and Discussion

Upon purification of compounds 34, 49, and 50, 1x10-5 M solutions of each were made and their absorption spectra were recorded (figure 45).

Figure 45. Absorbance spectra of compounds 34, 49, and 50.

Compound 49, consisting of only the anthracene chromophore, has three absorption bands centered at 365, 386, and 410 nm. Compound 50, consisting of only the corannulenylethynyl chromophore, has a two prominent absorption bands centered at 308 and

368 nm with a shoulder extending to 400 nm. The absorption spectrum of compound 34, with both chromophores, is a combination of the previous two compound's absorption spectra. The ethynylanthracene on compounds 34 and 49 do not red-shift the absorbance far enough to fluoresce green light. The ethynylanthracene is only 10 nm more red-shifted than the absorbance of 50. The addition of both chromophores (34) does not lead to an overall increase in the red-shift when compared to 49 and 50.

To gain further insight into the absorption spectra of the target compound 34, we performed density functional theory (DFT) and time-dependent-density functional theory (TD-

DFT) calculations. As a comparison, we also performed the same calculations on compound 33

(insulated with bicyclo[2.2.2]octane). We employed the B3LYP exchange-correlation functional with a 6-31G* basis set, as implemented in the Gaussian 03 suite of programs.52 Again, we chose the B3LYP theory with 6-31G* basis set because it accurately reproduces bond lengths, bond angles, and dihedral angles for corannulene, and therefore should give us accurate geometrical outputs.53 The B3LYP/6-31G* geometry optimized structures of 33 and 34 are shown in figure 46.

Figure 46. B3LYP 6-31G* geometry optimized structures of 33 and 34.

From the side view of the geometry optimized structures, we can see that the corannulenylethynyl substituted benzene side of the structures is nearly planar and should have maximum overlap in the π-system. This trend is similar to the para-substituted benzene compound (13) and bis(corannulenylethynyl)anthracene (21) seen in previous chapters. The anthracene unit in compound 33 is twisted 56° with respect to the benzene, whereas the anthracene unit in compound 34 is twisted 90° with respect to the benzene moiety. The greater twist angle in 34 can be contributed to anthracene unit fitting into the aromatic rings of the larger triptycene "insulating linker."

TD-DFT calculations of 33 predicts significant absorption bands centered at 414.21 nm

(f= 0.5117), 401.87 nm (f=0.6548), 363.18 nm (f=0.1783) and 317.43 nm (f=0.6504). The HOMO to LUMO transition 419.89 nm (f=0.0127) is not a relevant transition in this molecule. The calculated transition at 414.21 nm corresponds to the HOMO (-1) to LUMO transition. The calculated transition at 401.87 nm corresponds to the HOMO to LUMO (+1) transition. To

81 provide greater insight into these orbital transitions of 33, their positions on the molecule were calculated (figure 47).

Figure 47. HOMO to LUMO (+1) and HOMO (-1) to LUMO transitions for 33.

These orbital transition correlate nicely with the calculated numbers. The HOMO to LUMO transition is not relevant since the two orbitals are on different chromophores. However, the

HOMO to LUMO (+1) transition (414.21 nm) is entirely on the anthracene unit. The HOMO (-1) to LUMO transition (401.87 nm) is entirely on the corannulenylethynyl substituted benzene unit.

TD-DFT calculations of 34 predicts significant absorption bands centered at 413.65 nm

(f=0.4638), 399.16 nm (f=0.7754), 364.33 nm (f=0.2500), 318.87 nm (f=0.7068), and 310.35 nm

(f=0.2899). Like 33, the HOMO to LUMO transition 410.10 nm (f=0.0000) is not a relevant transition in this molecule. The calculated transition at 413.65 nm corresponds to the HOMO to LUMO (+1) transition and matches well with the observed peak at 409 nm. The calculated

82 transition at 399.16 nm corresponds to the HOMO (-1) to LUMO transition and corresponds to the observed peak seen at 387 nm. The observed peak centered at 369 nm corresponds with the calculated transition 364.33 nm. There is also an observed peak centered at 308 nm in the absorbance spectrum correlating with the calculated transition of 310.35 nm. To provide greater insight into these orbital transitions of 34, their positions on the molecule were calculated (figure 48).

Figure 48. HOMO to LUMO (+1) and HOMO (-1) to LUMO transitions for 34.

Again, the HOMO to LUMO transition is not relevant since the orbitals are positioned on different chromophores. The HOMO to LUMO (+1) transition (413.65 nm) is entirely on the anthracene unit. The HOMO (-1) to LUMO transition (399.16 nm) is entirely on the corannulenylethynyl substituted benzene unit.

The fluorescence spectra of compounds 34, 49, and 50 were recorded at 300, 365, 385, and 405 nm and the viability of the compounds to emit different wavelengths of light was determined by exciting the compounds with 405 and 442 nm lasers (figure 49).

Figure 49. Fluorescence of compounds 34, 49, and 50 with excitation at 405 and 442 nm.

The fluorescence spectra of compounds 34, 49, and 50 each show emission peaks in the 400-

500 nm region. Compound 49 has three peaks centered at 409, 433 and 447 nm. Compound

50 has two peaks centered at 412 and 432 nm respectively. The target compound 34 has the same three peaks as 49 centered at 410, 433, and 447 nm. Since each compound has a maximum absorption center around 410 nm, neither fluoresces at 442 nm, hence only light scattering is observed. When excited with a 405 nm laser, each compound fluoresces the same bluish color. It can be concluded that there isn't enough conjugation on the anthracene side of the molecule in order for green emittence to occur.

Since the anthracene unit gave only 10 nm more red-shift than the corannulenylethynyl substituted benzene, the need for more conjugation on the middle anthracene ring led to the synthesis of compound 51. The overall purification of 51 was not completely successful, however, based off MALDI-TOF-MS we were able to synthesize our target compound (Figure

50).

Figure 50. MALDI-TOF spectrum of compound 51.

The absorbance of the unpurified 51 was taken to see if the added conjugation led to an increase in the red-shift of the anthracene chromophore when compared to 34 (figure 51).

Figure 51. Absorbance spectra of compounds 34 and 51.

Figure 51 compares the absorbance spectra of compounds 34 and 51. The additional corannulenylethynyl unit on 51 allows for an overall-red shift in the absorbance. The maximum wavelength of absorbance for 34 was determined to be centered at 410 nm. However, 51 has a broad shoulder that extends to approximately 480 nm--giving an overall red-shift of 70 nm contributed to the additional corannulenylethynyl moiety. This additional conjugation is needed to allow for the compound to emit in the green region of the electromagnetic spectrum.

Density functional theory (DFT) and time-dependent-density functional theory (TD-DFT) calculations were then performed on 51. The geometry optimized structure was calculated and is shown in figure 52.

Figure 52. B3LYP 6-31G* geometry optimized structures of 51.

From the optimized geometry, it can be seen that the anthracene side of 51 resembles that of the other substituted anthracene structures, i.e. 21 and 30. In addition, the benzene side of 51 is similar to the optimized geometry of 1,4-bis(corannulenylethynyl)benzene (14).

TD-DFT calculations of 51 predicts significant absorption bands centered at 508.49 nm (f

= 1.1630), 399.45 nm (f = 0.9270), 364.48 nm (f = 0.2577), 319.02 nm (f = 0.7834), and 310.24 nm (f = 0.3195). Looking at the calculated orbitals, we can see that the 508.49 nm peak corresponds to the HOMO to LUMO transition and is positioned on the anthracene side of the compound. The other relevant transition at 399.45 nm corresponds to the HOMO (-1) to LUMO

(+1) transition and is located on the benzene side of the compound (figure 53). The extended conjugation gave an increase of nearly 100 nm for the lowest significant energy transition when compared to 34 (508 nm vs 413 nm).

Figure 53. HOMO, LUMO, HOMO (+1), and LUMO (-1) transitions of 51.

The fluorescence spectra of compounds 51 was taken in 10 nm increments between

400-480 nm with the addition of 370 nm and 488 nm (figure 54).

Figure 54. Fluorescence spectra of 51.

When excited at the lower wavelength of 370 nm, two distinct emission bands are seen centered at 414, and 437 nm with a third starting to emerge at 463 nm. However, when excited with increasing wavelengths, the two bands centered at 414 and 437 nm disappear with the emergence of two bands centered at 480 and 510 nm respectively. It can been seen that when excited between 430-450 nm only the bands centered at 480 and 510 nm can been seen.

In addition, when excited at 488 nm, only slight emission is detected. The compound was subjected to excitation by laser at 405, 442, and 488 nm lasers. When excited at 405 nm dark, intense blue emission is observed. When excited at 442 nm slightly less intense bluish/green

89 emission is observed. Additionally, mostly light scattering is observed when excited at 488 nm but with slight green fluorescence.

Conclusions

In order to alleviate the mixing of orbitals in the anthracene series (chapter 3), compounds with insulating linkers were designed and synthesized. To such insulating linkers

(used for their rigidity) were bicyclo[2.2.2]octane and triptycene. TD-DFT calculations were performed and the results for each compound were comparable for compounds 33 and 34. In each case, the HOMO to LUMO transition was not a relevant transition since each orbital was located on different chromophores. However, the HOMO to LUMO (+1) and the HOMO (-1) to

LUMO transitions for each were relevant. Synthetically, the compound containing the triptycene linker was less complicated and more straightforward so it was chosen for further studies.

Unfortunately, the absorbance spectra for 34 was very similar to the two standard compounds 49 and 50. Furthermore, each of the three compounds (34, 49, and 50) fluoresced the same bluish color when excited at 405 and 442 nm. It was determined that more conjugation was need to place on the anthracene side of the molecule. An addition corannulenylethynyl moiety was added to get compound 51. When looking at the calculated orbitals, we see that the HOMO to LUMO transition is on the anthracene side of the molecule and corresponds to the predicted 508 nm transition. We also see that the HOMO (-1) to LUMO

(+1) transition is located on the benzene side of the molecule and corresponds to the predicted

399 nm transition. The absorption spectra shows a red-shift of nearly 70 nm when the

90 additional conjugation is added when compared to 34. When looking at the fluorescence of 51, we see three distinct peaks centered at 414, 437, and 480 nm. When excited at 370 nm, only the peaks at 414 and 437 are present. When excited at progressively longer wavelengths, those to peaks start to disappear, with the emergence of the peak at 480 nm. When excited with

405, 442, and 488 nm lasers, the fluorescence becomes less blue and more green.

Unfortunately again, we do not have enough conjugation to reach all the way into the green region of the spectrum. However, it has been demonstrated through the fluorescence spectra, that the proof of principle is there.

CHAPTER 5

SUBSTITUTED PENTACENES: SYNTHESIS, STRUCTURE, AND PROPERTIES

Background

As mentioned before, for OLED displays, three primary colors need to be produced-- blue, green, and red. Building off our success with corannulene-based organic blue emitting molecules and our corannulene-based organic molecules that emit different wavelengths of light, we set with two goals:

1) Produce a corannulene-based organic molecule that could emit red light, and,

2) Design a system that could have the possibility of emitting all three colors--red, green,

and blue.

In order for red light to be emitted, larger conjugated systems need to be devised. As mentioned in chapter 3, Haley and co-workers have produced graphdiyne-based structures whose large conjugated systems consisting entirely of diynes and phenyl rings have shown the ability to be fine tuned to emit a variety of colors.45-46 By using strategically placed electron- donating and electron-withdrawing substituents on the frameworks, they were able to successfully fine tune the optical emitting properties (figure 25).46

The first red OLEDs were developed by Tang and co-workers and featured a pyran-based fluorescent dye as an active emitting material in a guest-host system.62 However, their broad- emission spectra gave them poor chromaticity. Other red-emitting systems have been developed based on various metals. Although good materials for light emitting, their use of

92 heavy metals is a major drawback. OLEDs based on linear acenes have been shown to give narrow emission bands with moderate fluorescence. However, displays are still dependent upon improving the efficiency, color purity, and operational stability of red OLEDs.

John Anthony and co-workers have successfully functionalized linear acenes to emit a variety of colors. For OLEDs, there is a constant need for new and promising materials to emit blue, green, and red. It has been shown that functionalized tetracenes and pentacenes lead to red emission. Anthony and co-worker functionalized tetracene and pentacene, substituted in various positions (figure 55).63-65

Figure 55. Substituted tetracene and pentacene derivatives.

These linear acenes are used for the typical high fluorescence efficiency that make them ideal emitters. The most prevalent method for the ethynylation of aromatic compounds involves

Sonogashira coupling between a terminal alkyne and an aryl bromide or iodide. Unfortunately, this method results in the formation of ring-fused side products when applied to halides on the peri position of linearly fused systems.66 We avoid these confounding side products by adopting an alternative procedure to palladium catalyzed coupling reactions. The addition of a lithium

93 acetylide to an acenequinone, followed by deoxygenation with stannous chloride, provides the diethynyl acene. Although linear acenes degrade over time, the addition of substituents increase their stability substantially.

Novel corannulene substituted, pentacene-based organic materials were designed to emit red light. Since substituted corannulenylethynyl benzene derivatives (chapter 2) emit blue light, and substituted anthracene derivatives (chapter 3) emit green light, a pentacene-based compound was designed to incorporate both chromophores (figure 56). This compound was designed with the hopes of producing a molecule that could emit all three needed colors for displays--red, green, and blue.

Figure 56. Proposed structure of three chromophore compound.

Synthesis

In a similar process used to make previous molecules, 6,13-bis(phenylethynyl)pentacene

(52) was synthesized (scheme 26).

Scheme 26. Synthesis of 52.

Pentacenequinone was synthesized in a reaction using α,α,α',α'-tetrabromo-o-xylene with benzoquinone. Reaction of pentacenequinone with the lithiated phenylacetylene gave the corresponding diol in 85% yield. Subsequent dehydration of the diol with SnCl2 in 50% aqueous acetic acid gave 52 in 50% yield as a blue solid.

Following a similar synthetic procedure, 6,13-bis(corannulenylethynyl)pentacene (57) was attempted to be synthesized (scheme 27).

Scheme 27. Proposed synthesis of 57.

Pentacenequinone was treated with lithiated TMS-acetylene under anhydrous conditions to yield the corresponding diol (53). Coupling of iodocorannulene was attempted after deprotection of the TMS group, to the diol without success. It was hypothesized that protection of the alcohol groups was necessary in order for the coupling to take place.

Therefore, the alcohols on 53 were protecting using TBDMS-Cl producing 54. Subsequent deprotection of the TMS group yielded the di-alkyne (55). Sonogashira coupling of iodocorannulene to 55 did not yield the desired product. Therefore, the dehydrogenation reaction could not be carried out to produce the final product (57). Another protecting group, dihydropyran (DHP), was also attempted to protect the alcohol groups in order to determine if

96 that was the cause of the inability to couple successfully. Unfortunately, the coupling did not occur with this protecting group as well.

Results and Discussion

Attempts were made to fully characterize the compound produced during the coupling reaction. The UV-Vis and fluorescence spectra were recorded and compared to corannulene and 1,4-bis(corannulenylethynyl)benzene (14) (figure 57).

Figure 57. UV-Vis and fluorescence spectra of corannulene, 1,4- bis(corannulenylethynyl)benzene and unknown coupling product.

Through the UV-Vis spectrum it can be concluded that the unknown coupling product has similar peaks to that of the two comparison molecules. Furthermore, the fluorescence spectra of the unknown has a similar emission spectrum to that of corannulene. Therefore, it can be hypothesized that the unknown compound is corannulene-based. Further analysis of the compound with 1H NMR and ES-MS gave the determination that the unknown compound was the palladium complex (25) encountered during the substituted anthracene series. The instability of the larger linear acenes was one major drawback. Coupling at higher temperature led to the degradation of the starting materials, were as, coupling at lower temperatures gave the undesired palladium complex (25).

After purification the absorbance spectrum of 6,13-bis(phenylethynyl)pentacene (52) was recorded (figure 58).

Figure 58. Absorbance spectrum of 52.

From the absorbance spectrum, two distinct peaks centered at 610 and 665 nm can be seen in the red region of the spectrum. To determine the viability of this compound and other such compounds as red emitters, the fluorescence spectra were recorded and the compound was excited with a 633 nm laser (figure 59).

Figure 59. Fluorescence spectra of 52.

When excited at 500 nm (green region) no fluorescence is detected. However, when excited at longer wavelengths, i.e. 600, 633, and 650 nm, fluorescence is detected with an emission peak centered at 672 nm. When excited with an 633 nm laser, bright, intense red fluorescence is observed.

Density functional theory (DFT) and time-dependent-density functional theory (TD-DFT) calculations were performed for the compound with all three chromophores. The geometry

99 optimized structure were calculated at the B3LYP 6-31G* level of theory (figure 60). The most relevant transition were calculated and shown in figure 61.

Figure 60. B3LYP/6-31G* calculated optimized geometry of three chromophore compound.

Figure 61. Calculated orbital transitions of three chromophore compound.

100

From figure 61, we can see that there are 3 significant transitions. The HOMO to LUMO transition is primarily located on the central pentacene ring and should correspond to a red emission. The HOMO (-1) to LUMO (+1) transition is primarily located on the anthracene ring system and should correspond the a green emission. The HOMO (-2) to LUMO (+2) transition is located primarily on the corannulene ring system and should correspond to blue emission. The theoretical calculations for this compound seem to point to the ability for this compound to contain all three chromophores. The TD-DFT calculations predict significant orbital transitions at 823.55 nm (f = 0.5309), 544.08 nm (f = 0.1810), 467.92 nm (f = 0.2961), 351.37 nm (f =

0.1403), 319.22 nm (f = 0.7130), 312.71 nm (f = 0.1935), and 293.12 nm (f = 0.3067) as shown in the theoretical UV-Vis spectrum (figure 62).

Figure 62. Theoretical UV-Vis spectrum of three chromophore compound.

The orbital transition predicted to be at 823.55 nm corresponds to the HOMO to LUMO transition positioned on the pentacene ring. The orbital transition predicted to be at 467.92 nm corresponds to the HOMO (-1) to LUMO (+1) transition positioned on the anthracene ring.

101

The orbital transition predicted to be at 319.22 nm corresponds to the HOMO (-2) to LUMO (+2) transition primarily positioned on the corannulene ring system.

Conclusions

Pentacene-based compounds were designed and synthesized as potential red-emitting organic materials. Substitution of phenylethynyl substituents in the 6,13 positions of pentacene gave absorbance between 600-700 nm which led to red emittence when excited with a 633 nm laser. Attempts were made to substitute corannulenylethynyl substituents in the 6,13 positions of pentacene with limited success. Attempted coupling of iodocorannulene with 6,13-bisethynylpenta-6,13-diol at low temperatures resulted in the formation of the palladium complex (25) seen previously in the anthracene series and at elevated temperature gave degradation of starting material. The coupling was also attempted after protection of the diols with no success.

Time dependent (TD) and time-dependent density functional theory (TD-DFT) calculations were preformed on a theoretical compound consisting of a pentacene, anthracene, and corannulene chromophores. The geometry optimized structure looked promising, so the orbital transitions were conducted. Three distinct orbital transition were observed, one centered primarily on the central pentacene, one centered on the anthracene ring system, and the last centered on the corannulene moiety. Each orbital transition corresponds to a significant transition as predicted in the theoretical UV-Vis spectrum.

Since substituted tetracene and pentacene structures have been shown to emit red light, they are crucial to the development of robust and stable light emitters. Corannulene-

102 based organic light emitters have also been shown to be robust and stable. Therefore, designing and synthesizing a corannulene-substituted pentacene structure should lead to a robust and stable platform for red emission. Furthermore, we have seen that corannulene- based anthracene structures have given multiple fluorescences when excited at different wavelengths. Based off the theoretical spectrum, the compound with all three chromophores present, should gave multiple fluorescences as well. Additional synthetic work needs to be performed in order to successfully synthesize the target compound.

103

CHAPTER 6

PHOTOCHEMICAL REACTIONS OF CORANNULENE

Background

Complexation of corannulene with halogen radicals

Corannulene's ground state chemistry is most consistent with benzene and other planar aromatic hydrocarbons. On the other hand, C60's ground state chemistry imitates that of an electron poor double bond. Although corannulene has different chemical reactivity to that of

C60 , their photochemical and physicochemical properties are strikingly similar. Particularly, both have exciting electrochemistry with corannulene being able to be reduced four times based on its doubly-degenerate low-lying LUMO. Similarly, C60 has a triply-degenerate low-lying

LUMO which can be reduced six times. It has been shown that upon photoexcitation, C60 gives rapid inter-system crossing to the triplet state. The study of the photochemistry and photophysical properties of C60 has been extensively studied. It has also been shown that by derivatizingC60 , the lifetime of the triplet state can be fine tuned for different applications.

Unfortunately, the photochemistry of corannulene has not been extensively studied.

Corannulene suffers from a low fluorescence lifetime and quantum yield which can be attributed to the singlet state inter-system crossing to the triplet. The complexation of bromine and chlorine radicals with corannulene were explored to determine if the isolated photoproducts of the excited state corannulene produced photoreactivity based on the singlet excited state similar to benzene or the triplet excited state similar toC60 .

104

Corannulene-based cis/trans isomerization

Studies of photoinduced trans-cis isomerization is long been known. An understanding on trans – cis isomerization helps in designing molecular photswitches, phototriggers, and data storage devices. C60 dimers, for example, undergo cis-trans isomerization upon irradiation with

67 UV-Vis light . Photo-switchable C60 dimers were synthesized which were connected through an azo-bridge (figure 63).

Figure 63. Photo-switchable C60 dimer.

Although photo-switchable C60 dimers have been studied, there is limited research on the cis- trans isomerization of corannulene derivatives. The potential for cis-trans isomeriztion of corannulene-based derivatives were undertaken using alkenes. Further studies were conducted using corannulenes linked through an azo bridge.

Synthesis

Corannulene (7) was synthesized according to the method previously shown in Chapter

1. In addition acetylcorannulene (58) and benzoylcorannulene (59) were also synthesized

(scheme 28).

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Scheme 28. Synthesis of acetylcorannulene (58) and benzoylcorannulene (59).

Corannulene was reacted with the appropriate acid chloride in the presence of Aluminum chloride to produce 58 and 59.

For the photo-induced cis-trans isomerization project, 1-corannulenyl-1-propene (61) and 1-corannulenyl-3-phenylpropenone (62) were synthesized (scheme 29).

106

Scheme 29. Synthesis of 1-corannulenyl-1-propene (61) and 1-corannulenyl-3- phenylpropenone (62).

Corannulene was treated with ,-dichloromethyl methyl ether and titanium tetrachloride in anhydrous methylene chloride to produce corannulenealdehyde (60). From the aldehyde, 61 and 62 were synthesized utilizing the Wittig reaction by reacting it with the appropriate phosphonium salt.

Results and Discussion

Complexation of corannulene with halogen radicals

Photolysis of corannulene in argon-saturated hexane and acetonitrile did not yield any photoproducts. However, photolysis of corannulene in chloroform led to the formation of a

107 mono-chlorinated corannulene compound. Similarly, the photolysis of corannulene in bromoform resulted in the mono-brominated corannulene compound. When performing the same studies in oxygen-saturated chloroform or bromoform solutions, the same photoproducts were produced--indicating that the products are not formed from the triplet excited state (T1)

(oxygen quenches triplet states). When incorporating a built-in triplet sensitizer (compound 58) the photolysis did not yield any new photoproducts in argon or oxygen saturated acetonitrile or chloroform solutions. Therefore, it is theorized that upon irradiation of corannulene, the energy from the singlet excited state (S1) undergoes energy transfer to the solvent directly competing with inter-system crossing to the T1 excited state. The energy transfer from corannulene to chloroform and bromoform results in the formation of chlorine and bromine radicals that react with corannulene (scheme 30 and 31).

Scheme 30. Photolysis of corannulene with chloroform and bromoform.

108

Scheme 31. Photolysis of corannulene with chloroform and bromoform.

To fully understand the photoreactivity of corannulene and acetylcorannulene and how corannulene complexes bromine and chlorine radicals, calculations were performed at the

B3LYP level of theory using 6-31+G(d) as the basis set.52,68 TD-DFT calculations of corannulene located its S1 at 85 kcal/mol above its S0, which fits with experimental results that place band of fluorescence at 81 kcal/mol above S0. In addition, the optimized T1 of corannulene was found to be 61 kcal/mol above S0 which correlates excellently with the experimental value of 60 kcal/mol. TD-DFT calculations of 58 place S1 at 73 kcal/mol and S2 at 76 kcal/mol. Inspection of the molecular orbitals shows that S1 is the excited singlet ketone (S1K) and S2 is the excited state

(S1C) that is localized on the corannulene moiety. The optimized structure of 58 places the T1K at 58 kcal/mol above S0. Visualization of the orbitals shows that T1K of 58 has (π-π*) configuration. In comparison, T1C for 58 is located 55 kcal/mol above its S0 and it C=O bond of

1.234 Å and the calculated vibrational band is at 1575 cm-1.

109

When studying the complex formed between corannulene with bromine and chlorine radicals, two different radical/corannulene π-complexes were observed. The π-complexes with the chlorine atom located on the rim on the concave surface of corannulene and has a C-Cl bond of 2.768 Å. There were also four σ-complexes for chlorine/corannulene complexes, with

σ-1 has the chlorine atom on the rim on the concave side of corannulene and has the lowest energy and it is approximately 2 kcal/mol lower in energy than the π-1. σ-2 has the chlorine atom on the rim of the concave side of corannulene and is ~2 kcal/mol higher in energy than σ-

1. Similarly, the σ-3 and σ-4 have the Cl atom on the hub of corannulene on the convex and the concave side, respectively. σ-3 is 2.4 kcal/mol higher in energy than σ-1 whereas σ-4 is 10.6 kcal/mol. The C-Cl atom bond lengths in the σ-complexes ranges from 1.89 to 3.13 Å (figure

64).

Figure 64. Halogen/corannulene complexes.

110

We calculated the transition state for the chlorine atom in σ-3 migrating around the hub and found that it is located 2.6 kcal/mol above σ-3. Similarly, we calculated the transition state for the Cl atom walking around the rim in σ-1 which is located 1.6 kcal/mol above σ-1.

Furthermore, the transition state for inversion of the σ-3 to σ-4 is located 13.3 kcal/mol above

σ-3. In comparison, when we calculated the transition state barrier for ring inversion of corannulene it was found to be 9.3 kcal/mol. Additionally, the optimized structures of ·CHBr2 and ·CHCl2 radicals and their photoproducts and plotted them (figure 65).

Figure 65. Energy diagram for the singlet and triplet surface of corannulene and 58.

111

Laser flash photolysis of corannulene in argon saturated acetonitrile produced a transient absorption spectrum with λmax at 350, 410 and 550 nm. TD-DFT calculations of T1 of corannulene support that the bands at 410 and 550 nm are due to T1. Furthermore, laser flash photolysis of corannulene in oxygen saturated acetonitrile results in a different transient spectrum with λmax at 350 nm, with the bands at 410 and 550 nm being quenched (figure 66).

Thus, it can be concluded that the bands at 410 and 550 nm can be assigned to the T1 of corannulene. Since the absorption with λmax at 350 nm was not quenched in oxygen, it is assigned to S1 of corannulene. Similar results were obtained in hexane as well.

Argon 0.2 Oxygen O.D.

Δ 0.0

-0.2

300 350 400 450 500 550 600 Wavenlength [nm]

Figure 66. Laser flash photolysis of corannulene in argon and oxygen saturated acetonitrile.

The laser-flash photolysis of 58 in argon saturated solvents resulted in a transient absorption that formed faster than the resolution of the laser. This transient absorption was quenched in oxygen saturated solution, thus being assigned to the T1 of 58.

112

Corannulene-based cis/trans isomerization

Photolysis of 61 in argon saturated chloroform-d solution yielded 60

(corannulenealdehyde) as the major product (scheme 32). Irradiation of 61 in oxygen saturated chloroform-d solution also yielded 60 as the primary product. However, the conversion to 60 in oxygen-saturated solutions occurs at a much greater rate when compared to argon saturated solutions.

Scheme 32. Photolysis of 61.

The conversion in oxygen saturated solution occurs in less than 1 h, whereas the conversion in argon saturation solution occurs in 4 h. The slower conversion can be attributed to the fact of low oxygen levels in the argon saturated solutions. Performing the experiments using a Pyrex filter ensures that only the alkene absorbs the light and forms a singlet excited state of the corannulene (S1C) in 61. Theoretically, the irradiation of 61 should cause the cis-trans isomerization to occur (scheme 33).

113

Scheme 33. Proposed cis-trans isomerization of 61.

Scheme 34 shows the proposed mechanism to account for the formation of the corannulene aldehyde.

Scheme 34. Proposed mechanism for the formation of corannulene aldehyde.

Since the cis-trans isomerization does not occur, further studies were conducted into the oxidation product formed. To fully understand the reactivity of 61 calculations of the triplet surface at the B3LYP level of theory with the 6-31+G(d) basis set were used. The calculations should allow the identity of the most favorable reaction on the triplet surface and allow for the understanding of the factors that control the reactivity of the triplet surface of 61. This energy profile will determine the more feasible pathway for the addition of oxygen (scheme 35).

114

Further, the singlet energy surface was also calculated for the addition of one singlet oxygen

(scheme 36).

51 a 53 TBR

. . b 32

3 + O2 c 18

3O + 2

-76

. O O O O O . . a = H O b = c = O O. + H

Scheme 35. Energy profile for triple surface for addition of oxygen.

0 . -8 O O.

1 + O2

-46 O O

-115

O H O

+ H

Scheme 36. Energy profile for singlet surface for addition of oxygen to alkene.

115

Photolysis of 62 in an argon-saturated chloroform-d solution yielded the same corannulene aldehyde product that 61 produced. Additionally, same amounts of benzaldehyde and benzoic acid were also produced (scheme 37).

Scheme 37. Photolysis of 62.

Similar to 61, photolysis of 62 in an oxygen saturated chloroform-d solution gave the same products with faster conversion times. Energy transfer from T1C to the alkene moiety forms a triplet biradical (TBR) of 62, which undergoes oxygen addition and then presumably cleaves to form aldehyde 60, benzoic acid, and benzaldehyde in the same as manner 61 (schemes 35 and

36). Laser flash photolysis studies of 61 and 62 in different solvents further support the proposed reaction mechanism.

The incorporation of an azo-bridge (similar to the C60 system) should allow for cis-trans isomerization to occur without the unwanted oxidation (figure 67).

Figure 67. Proposed structure of azo connected corannulene for cis-trans isomerization.

116

Calculating the energies of T1C, T2C and TBR for the azo connected compound shows that the TBR is not higher than the optimized energy of T1C. Furthermore, the energy difference of

T1C and T2C is not as large for this molecule as seen in previous ones. Therefore, it is theorize that this compound would be a better candidate for cis-trans isomerization.

Conclusions

The photochemical reactivity of corannulene is consistent with that of benzene. That is, the energy from the singlet excited state (S1) undergoes energy transfer to the solvent directly competing with inter-system crossing to the T1 excited state. The energy transfer from corannulene to chloroform and bromoform results in the formation of chlorine and bromine radicals that react with corannulene. When the same experiments were carried out in non- halogenated solvents, no photo products were observed. Several calculation were conducted to fully understand the photoreactivity of corannulene and acetylcorannulene and how corannulene complexes bromine and chlorine radicals with calculations performed at the B3LYP level of theory using 6-31+G(d) as the basis set. Laser flash photolysis of corannulene in argon saturated acetonitrile produced a transient absorption spectrum with λmax at 350, 410 and 550 nm. It was determined that the bands at 410 and 550 nm can be assigned to the T1 of corannulene. Since the absorption with λmax at 350 nm was not quenched in oxygen, it is assigned to S1 of corannulene.

The cis-trans isomerization of compounds 61 and 62 did not undergo the expected transformation. It was determined that upon irradiation, energy transfer from T1C to the alkene moiety forms a triplet biradical (TBR), which undergoes oxygen addition and then presumably cleaves to form corannulene aldehyde. Laser flash photolysis studies of 61 and 62 in different

117 solvents further support the proposed reaction mechanism. When conducting calculations on an azo-connected corannulene compound, the energy profile is found to be conducive to undergo the preferred cis-trans isomerization. Calculating the energies for the azo connected compound shows that the TBR is not higher than the optimized energy of T1C. Therefore, it is theorize that this compound would be a better candidate for cis-trans isomerization.

118

CHAPTER 7

EXPERIMENTAL METHODS

Instrumentation and Materials

Column chromatography was carried out using an Isco Combiflash Companion column system with silica gel columns purchased from Silicycle Inc. 1H NMR and 13C NMR spectra were recorded on a Bruker Avance 400 spectrometer. Deuterated NMR solvents were obtained from

Cambridge Isotope Laboratories, Inc., Andover, MA, and used without further purification.

Molecular masses were determined by a Hewlett Packard 6890 series GC with a 5972A mass selective detector, Bruker Biflex III matrix-assisted laser desorption-ionization time of flight mass spectrometer (MALDI-TOF-MASS) with a tetracyanonapthaquinone matrix or an anthracene matrix or a micromass Q-Tof-2 electrospray mass spectrometer. Absorption and emission spectra were measured in CH2Cl2 in a 1-cm path quartz cell using a Cary 50 UV-Vis spectrophotometer and a Cary Eclipse fluorescence spectrophotometer respectively.

Luminescence studies were conducted using a Power Technologies 405 nm laser and a Melles

Griot 488 nm laser. Diethyl ether, tetrahydrofuran, toluene, and dichloroethane were purified from an MBraun solvent purification system. Thermal gravametric analysis (TGA) and differential scanning calorimetry (DSC) was conducted using a Netzsch STA 409 PC/PG.

NiCl2(dppp), Pd(PPh3)4, and PdCl2(PPh3)2 were purchased from Strem and used without further purification. Other reagents were purchased from either Acros or Sigma-Aldrich and used without further purification.

119

Synthetic Procedures

2,7-dimethylnaphthalene (2)

Modified procedures as prepared by the published method.18 Into a 1-L round-bottom flask, 2,7-dihydroxynaphthalene (49.7g, 0.310 mol), pyridine (500mL) and diethylcarbamoylchloride (120 mL) is added and refluxed overnight. The solution is then poured into a 2-L beaker containing a solution of hydrochloric acid (6M, 600mL). A light brown solid, which solidified out of solution, was filtered using a Buchner funnel, washed with water and dried overnight. The resultant product is a light brown solid and used without further purification(110.86g, 99%). An oven-dried 2-L round-bottom flask is equipped with a reflux condenser and an oven-dried dropping funnel. Under a flow of nitrogen, the flask is charged with 2,7-bis(diethylcarbamoyloxy)naphthalene (90.42g, 0.253 mol), NiCl2(dppp) (2.44g), and anhydrous diethyl ether (500mL). The dropping funnel is charged with methylmagnesium bromide (3M in diethyl ether, 350mL), which is added dropwise over 30 min. The mixture is stirred at 40°C for 48 hours. The dropping funnel is charged with hydrochloric acid (6M, 400mL) and slowly added to the reaction over 1 hr to produce and maintain a gentle reflux. The aqueous layer is separated and extracted further with CH2Cl2. The combined organic layers are washed with water and dried over magnesium sulfate. The crude mixture was evaporated

1 under reduced pressure and purified with cyclohexane (35.4g, 90%). H NMR (400 MHz, CDCl3)

δ= 7.67 (d, 1H, J = 8.4 Hz), 7.49 (s, 1H), 7.21 (d, 1H, J = 8.4 Hz), 2.47 (s, 3H). 13C NMR (400 MHz,

CDCl3) δ= 135.4, 133.9, 129.9, 127.4, 127.2, 126.2, 21.7.

120

3,8-dimethylacenaphthenequinone (3)

17 Procedure followed as prepared in the published method. To a solution of CH2Cl2 (1.3

L) in a oven dried 2-L round-bottom flask was added aluminum bromide (141.1 g, 0.53 mol) under a flow of argon. The solution was stirred and cooled to -16° C using an ethylene glycol/CO2 bath. A solution of 2,7-dimethylnapthalene (44.2 g, 0.28 mol), oxalyl chloride (23.02 ml, 0.26 mol), and CH2Cl2 (150 mL) was added dropwise over 1 hr. The solution is kept at -16°C for an additional 4 hrs and then warmed to room temperature overnight. The solution was then carefully quenched by pouring into ice water. The organic layer is was with H2O, dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was passed through a silica plug using 1:1 CH2Cl2/Cyclohexane (1000 mL) to get rid of fast moving impurities, switching to 2:1 (2000 mL) CH2Cl2/Cyclohexane and finally to pure CH2Cl2 (1000 mL).

Fractions are collected in 500 mL portions and evaporated to yield a golden yellow solid (25.0 g,

42%) as a mixture of 3,8-dimethylacenapthenequinone and 4,7-dimethylacenaphthenequinone

1 (90/10). H NMR (400 MHz, CDCl3) δ= 8.01 (d, 1H, J = 8.4 Hz), 7.93 (s, 1H), 7.84 (s, 1H), 7.48 (d,

13 1H, J = 8.4 Hz), 2.85 (s, 3H) 2.67 (s, 3H). C NMR (400 MHz, CDCl3) δ= 188.6, 188.1, 146.9, 143.0,

143.0, 138.9, 137.4, 131.7, 131.0, 130.7, 130.5, 128.1, 127.3, 124.1, 122.4, 22.4, 18.0.

1,6,7,10-tetramethylfluoranthene (4)

Procedure followed as prepared in the published method.19 A 20% solution of potassium hydroxide in methanol (150 mL) is added to a solution of 3,8- dimethylacenaphthenequinone (15.8 g, 0.075 mol) and 3-pentanone (50 mL) in methanol (50 mL). The solution is stirred at room temperature for 1.5 hrs, diluted with water (250 mL) and

121 extracted with CH2Cl2. The organic layer is washed with 10% aqueous hydrochloric acid (100 mL), dried with magnesium sulfate, and evaporated under reduced pressure. The crude oil is transferred to a 350 mL sealable reaction vessel and 2,5-norbornadiene (30 mL) and acetic anhydride (100 mL) is added. The vessel is sealed and placed in an wax bath at 140° C for 3 days. The reaction is then cooled to room temperature and neutralized with 10% aqueous sodium hydroxide (100 mL x 2), washed with H2O (100 mL x 3) and extracted with CH2Cl2. The organic layers are combined, dried over magnesium sulfate and evaporated under reduced pressure to yield a dark brown oil. The oil is purified using a silica plug with cyclohexane as the solvent to give a golden yellow oil that solidifies upon standing (10.8 g, 56 %). 1H NMR (400

MHz, CDCl3) δ= 7.69 (s, 1H), 7.60 (d, 1H, J = 8 Hz), 7.43 (s, 1H), 7.27 (d, 1H, J = 8 Hz), 7.04 (s, 1H),

13 7.00 (s, 1H), 2.77 (s, 3H), 2.69 (s, 3H), 2.57 (s, 3H). C NMR (400 MHz, CDCl3) δ= 139.9, 137.5,

134.9, 133.7, 131.9, 131.8, 131.7, 130.6, 129.7, 129.6, 129.4, 126.6, 126.1, 124.6, 124.3, 25.1,

24.3, 22.6, 20.3.

1,6,7,10-tetrakis(dibromomethyl)fluoranthene (5)

Modified procedure as prepared by the published method.19 To a solution of carbon tetrachloride (300 mL) and 1,6,7,10-tetramethylfluoranthene (16.3 g, 0.063 mol) was added N- bromosuccinimide (112.5 g, 0.63 mol) and benzoyl peroxide (20 mg). The solution was irradiated with incandescent light (300 W) and refluxed for 4 days. The solvent is removed under reduced pressure and the solid dissolved in CH2Cl2 (200 mL), washed with water (100 mL x 3), dried over magnesium sulfate and evaporated under reduced pressure to yield a golden

1 yellow solid (50.6 g, 91%). H NMR (400 MHz, CDCl3) δ= 8.26 (d, 1H, J= 13.6 Hz), 8.19 (s, 1H),

122

13 7.97 (d, 1H, J = 13.6 Hz), 7. 19 (s, 1H), 7.07 (s, 1H). C NMR (400MHz, CDCl3) δ= 138.0, 136.6,

132.4, 131.9, 131.6, 130.2, 130.1, 129.2, 127.7, 39.0, 38.4, 29.5, 28.7.

1,2,5,6-tetrabromocorannulene (6)

Modified procedure as prepared by the published method.20 To a solution of 1,6,7,10- tetrakis(dibromomethyl)fluoranthene (30.0 g, 0.034 mol) in 1,4-dioxane (250 mL) was added sodium hydroxide (14.9 g) in H2O (200 mL). The solution was refluxed overnight. The solution is poured into hydrochloric acid (6M, 600 mL) and allowed to stir for 1 hr. The solution was then filtered with a Büchner funnel to give a light brown solid. The solid was washed with H2O then acetone and allowed to dry overnight (12.99 g, 68%)

Corannulene (7)

Modified procedure as prepared by the published method.20 To a stirred suspension of ethanol (500 mL) was added 1,2,5,6-tetrabromocorannulene (10.1 g, 0.02 mol), zinc dust (120 g), potassium iodide (43 g) and 25 mL 10% aqueous hydrochloric acid. The reaction mixture was refluxed for 48 hrs. The solution mixture was filtered and ethanol was removed under reduced pressure. The solid was dissolved in CH2Cl2 and washed with H2O (150 mL x 3), dried over magnesium sulfate and evaporated under reduced pressure to yield a yellow solid. The product was purified by column chromatography using a gradient cyclohexane- CH2Cl2 eluent to

1 13 provide a yellow solid (2.2 g , 50%). H NMR (400 MHz, CDCl3) δ= 7.76 (s, 10H). C NMR (400

MHz, CDCl3) δ= 135.8, 130.9, 127.1.

123

Bromocorannulene (8)

To a solution of corannulene (1.0 g, 4 mmol) in anhydrous 1,2-dichloroethane (150 mL) under a blanket of argon was added iodobromide (2.50 g, 12 mmol). The mixture was stirred at room temperature for a period of 16 hrs. The crude mixture was evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane- CH2Cl2 eluent

1 to provide a yellow solid (1.2 g, 90%). HNMR(400 MHz, CDCl3) δ = 8.03 (s, 1H), 7.93 (d, 1H, J =

13 8.6 Hz), 7.87–7.78 (m, 6H), 7.71 (d, J = 8.6 Hz, 1H) C NMR (CDCl3) δ = 122.1, 126.7, 127.2,

127.7, 127.9, 128.0, 128.4 (2C), 128.8, 130.1, 130.9, 131.5, 131.8 (2C), 132.7, 135.5, 135.8,

136.4, 136.6.

Iodocorannulene (9)

To a solution of bromocorannulene (0.6 g, 0.002 mol) in DMF (40 mL) was added CuI

(1.72 g, 0.009 mol) and potassium iodide (3.36 g, 0.020 mol). The solution was allowed to reflux for 48 hrs. The reaction was quenched with H2O and the solid filtered. The solid was washed with CH2Cl2 (300 mL x 2). The organic layer was washed with H2O (200 mL x 3), dried over magnesium sulfate and evaporated under reduced pressure. The solid is purified using column chromatography using a gradient cyclohexane- CH2Cl2 eluent to provide a yellow solid

1 as a mixture of iodocorannulene/bromocorannulene (80/20). H NMR (400 MHz, CDCl3) δ =

7.67-7.85 (m, 8H), 8.30 (s, 1H).

124

Ethynylcorannulene (10)

To a stirred solution of potassium carbonate (0.627 g, 4.54 mmol) in methanol (15 mL) was added (trimethylsilylacetylene) corannulene (0.524 g, 1.5 mmol) dissolved in CH2Cl2 (10mL).

The reaction was stirred for 0.5 hrs at room temperature. The crude reaction was treated with water (50 mL), and extracted with CH2CL2 (20 mL x 3). The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a cyclohexane eluent, which gave the title compound (0.386 g,

1 94%). H NMR (400 MHz, CDCl3) δ = 3.38 (s, 1H), 7.71–7.77 (m, 6H), 7.82 (d, J =8.8Hz, 1H), 7.97–

8.00 (m, 2H). 13CNMR(CDCl3) δ = 80.6, 81.8, 120.3, 126.0, 126.7, 127.3, 127.6, 127.7, 127.8,

130.2, 131.1, 131.2, 131.3, 131.4, 135.2, 135.6, 135.7.

1,2-Bis(corannulenylethynyl)benzene (11)

In a dry box with an argon atmosphere, to a pressure vessel was added 2-ethynyl-

(corannulenylethynyl)benzene (15) (0.08 g, 0.36 mmol), iodocorannulene (0.27 g, 0.72 mmol), copper iodide (0.007 g, 0.036 mmol), Pd(PPh3)4 (0.10 g, 0.09 mmol) triethylamine (5 mL) and anhydrous THF (15 mL). The pressure vessel was sealed, and the reaction stirred for 24 h at 75°

C. The crude mixture was washed with 10% HCl (3 × 10 mL), and extracted with CH2Cl2 (3 × 15 mL). The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent, which gave the title compound (0.08 g, 60%). HRMS: calcd for

1 C50H22, 622.1722 found [M+] 622.1778. H NMR (400 MHz, CDCl3) δ = 7.10 (d, J = 8.8 Hz, 1H),

7.46 (d, J = 8.8 Hz, 1H), 7.49 (d, J = 8.8 Hz, 1H), 7.62 (d, J = 8.8 Hz, 1H), 7.72–7.81 (m, 5H), 8.08

125

13 (d, J = 8.8 Hz, 1H), 8.11 (s, 1H). C NMR (CDCl3) δ = 92.2, 92.3, 121.4, 126.0, 126.3, 126.6, 127.1

(2C), 127.2, 127.4 (2C), 127.5, 128.3, 130.3, 130.8, 131.0, 131.1, 131.5 (2C), 132.2, 135.1, 135.4,

135.5, 135.7, 136.0.

1,3- Bis(corannulenylethynyl)benzene (12)

In a dry box with an argon atmosphere, to a pressure vessel was added 3-ethynyl-

(corannulenylethynyl)benzene (16) (0.58 g, 1.6 mmol), iodocorannulene (1.2 g, 3.1 mmol), copper iodide (0.03 g, 0.16 mmol), Pd(PPh3)4 (0.44 g, 0.38 mmol), triethylamine (5 mL) and anhydrous THF (15 mL). The pressure vessel was sealed and the reaction stirred for 24 h at 75°

C. The crude mixture was purified by column chromatography using a gradient cyclohexane–

CH2Cl2 eluent, which gave the title compound (0.58 g, 60%). HRMS: calcd for C50H22: 622.1722

1 found [M+] 622.1669 H NMR (400 MHz, CDCl3) δ= 7.69 (s, 2H), 7.74-7.88 (m, 7H), 8.05 (s, 1H),

13 8.11 (d, J= 8.8 Hz, 1H). C NMR (CDCl3) δ= 90.7, 93.6, 121.3, 123.5, 126.0, 126.1, 126.8,127.1,

127.3, 127.5, 127.6, 127.7, 130.3, 130.9, 131.0, 131.2, 131.3, 131.5, 131.9, 133.2, 135.4, 135.6,

135.9, 136.4.

1,4-Bis(corannulenylethynyl)benzene (13)

In a dry box with an argon atmosphere, to a pressure vessel was added 4-ethynyl-

(corannulenylethynyl)benzene (17) (0.58 g, 1.6 mmol), iodocorannulene (1.2 g, 3.1 mmol), copper iodide (0.03 g, 0.16 mmol), Pd(PPh3)4 (0.44 g, 0.38 mmol), triethylamine (5 mL) and anhydrous THF (15 mL). The pressure vessel was sealed, and the reaction stirred for 12 h at 75°

126

C. The crude mixture was washed with 10% HCl (3 × 10 mL), extracted with CH2Cl2 (3 × 15 mL), and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent, which gave the title compound

1 (0.58 g, 60%). HRMS: calcd forC50H22, 622.1722 found [M+] 622.1669. HNMR (400 MHz, CDCl3)

13 δ = 7.69 (s, 2H), 7.74–7.88 (m, 7H), 8.05 (s, 1H), 8.11 (d, J = 8.8 Hz, 1H). C NMR (CDCl3) δ =

90.7, 93.6, 121.3, 123.5, 126.0, 126.1, 126.8, 127.1, 127.3, 127.5, 127.6, 127.7, 130.3, 130.9,

131.0, 131.2, 131.3, 131.5, 131.9, 133.2, 135.4, 135.6, 135.9, 136.4.

(Corannulenylethynyl)benzene (14)

To a dry box under an argon atmosphere, to a pressure vessel was added phenylacetylene (0.09 g, 0.86 mmol), iodocorannulene (0.97 g, 2.58 mmol), Pd(PPh3)4 (0.19 g,

0.17 mmol), CuI (0.01 g, 0.07 mmol), anhydrous THF (15 mL), and Et3N (5 mL). The pressure vessel was sealed, and the reaction stirred for 24 h at 80° C. The crude mixture was washed with 10% HCl (3 × 10 mL), and extracted with CH2Cl2 (3 × 15 mL). The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent, which gave

1 the title compound (0.24 g, 80%). HNMR (400 MHz, CDCl3) δ = 7.23-7.42 (m, 3H), 7.65-7.68 (m

2H), 7.71-7.78 (m, 6H), 7.83-7.85 (d, J = 8.8 Hz, 1H), 8.03 (s, 1H), 8.09-8.11 (d, J = 8.8 Hz, 1H) 13C

NMR (CDCl3) δ = 87.7, 93.2, 121.4, 123.3, 126.0, 126.6, 127.1, 127.3, 127.4, 127.5, 128.5, 128.5,

130.3, 130.9, 131.1, 131.1, 131.8, 131.8, 135.1, 135.2, 135.6, 136.1.

127

4-bromo-(corannulenylethynyl)benzene (17)

To a dry box under an argon atmosphere, to a pressure vessel was added 4-bromo- ethynylbenzene (0.17g, 0.94 mmol), iodocorannulene (1.06 g, 2.82 mmol), Pd(PPh3)4 (0.27 g,

0.24 mmol), CuI (0.02 g, 0.09 mmol), anhydrous THF (10 mL), and Et3N (5 mL). The pressure vessel was sealed, and the reaction mixture stirred for 48 h at 60° C. The crude mixture was quenched by addition of hydrochloric acid (6M), washed with H2O (3 x 20 mL), and extracted with CH2Cl2 (3 × 15 mL). The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent, which gave the title compound (0.32 g, 80%). Compounds

1 15 and 16 are synthesized in exactly the same manner. HNMR (400 MHz, CDCl3) δ = 7.49-7.54

(m, 4H), 7.70-7.78 (m, 6H), 7.82-7.84 (d, J = 8.8 Hz, 1H), 8.01 (s, 1H), 8.04-8.06 (d, J = 8.8 Hz, 1H)

13 C NMR (CDCl3) δ = 88.9, 92.0, 121.0, 122.2, 122.7, 125.9, 126.6, 127.1, 127.4, 127.4, 127.5,

127.6, 130.2, 130.7, 130.9, 131.1, 131.1, 131.3, 131.7, 133.2, 135.1, 135.3, 135.6, 135.6, 136.1.

4-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (20)

To a dry box under an argon atmosphere, to a pressure vessel was added 4-bromo-

(corannulenylethynyl)benzene (0.17 g, 0.39 mmol), TMS-acetylene (0.17 mL, 1.9 mmol),

Pd(PPh3)4 (0.11 g, 0.09 mmol), CuI (0.01 g, 0.039 mmol), anhydrous THF (20 mL), and Et3N (10 mL). The pressure vessel was sealed, and the reaction mixture stirred for 48 h @ 60° C. The crude mixture was quenched by hydrochloric acid (6M), washed with H2O (3 x 20 mL), and extracted with CH2Cl2 (3 × 15 mL). The organic layer was dried over magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column

128 chromatography using a gradient cyclohexane–CH2Cl2 eluent, which gave the title compound

(0.16 g, 90%). Compounds 18 and 19 are synthesized in exactly the same manner. 1HNMR (400

MHz, CDCl3) δ = 0.28 (s, 9H), 7.49-7.51 (d, J = 8.8 Hz, 2H), 7.59-7.61 (d, J = 8.8 Hz, 2H), 7.74-7.81

(m, 6H), 7.85-7.87 (d, J = 8.8 Hz, 1H), 8.04, (s, 1H), 8.08-8.10 (d, J = 8.8 Hz, 1H).

9,10-Bis(corannulenylethynyl)anthracene (21)

In a dry box with an argon atmosphere, to a pressure vessel was added 9-bromo-10-

(corannulenylethynyl)anthracene (0.03 g, 0.057 mmol), ethynylcorannulene (0.03 g, 0.113 mmol), Pd(PPh3)4 (0.01 g, 0.008 mmol), CuI (0.001 g, 0.006 mmol), THF (5 mL), and Et3N (5 mL).

The pressure vessel was sealed, and the reaction mixture was stirred for 24 h at room temperature. The crude mixture was washed with 10% hydrochloric acid (2 x 25 mL), H2O (2 x

25 mL), extracted with CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound (0.01g, 20%). HRMS: calcd for

1 C58H26: 722.2034 found [M+] 722.1550 H NMR (400 MHz, CDCl3) δ= 8.94-8.91 (m, 2H), 8.39-

13 8.37 (m, 2H), 8.05-8.02 (d, J = 12.0 Hz, 1H), 7.93-7.87 (m, 6H), 7.82-7.80 (m, 2H) C NMR (CDCl3)

δ = 136.5, 136.2, 136.1, 136.0, 135.8, 135.6, 134.1, 132.5, 131.8, 131.4, 131.4, 131.1, 130.9,

130.9, 130.5, 128.1, 127.8, 127.8, 127.7, 127.4, 127.4, 127.3, 126.9, 126.3, 126.3, 121.7, 114.2,

101.9, 91.0.

129

9,10-bis(trimethylsilylethynyl)anthra-9,10diol (22)

To a 100 mL round-bottomed flask, under a flow of argon was added diethylether (40 mL), TMS-acetylene (1.4 mL, 10.58 mmol), and n-BuLi (6.60 mL, 9.62 mmol) and the solution was allowed to stir for 1 h at 0° C. Anthracenequine (1.0 g, 4.81 mmol) was then added and solution was allowed to stir for 24 h at room temperature. Reaction was quenched with 10% hydrochloric acid, washed with H2O (3 x 30 mL), and extracted with CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure (1.85 g, 95%). The crude product was used for the next step without further purification.

9,10-bis(trimethylsilylethynyl)anthracene (23)

To a 500 mL round-bottom flask, was added 22 (1.85 g, 4.58 mmol) and ethanol (150 mL) at stirred at room temperature. To the solution was added SnCl2 ▫ 2H2O (45.8 mmol) in

50% aqueous acetic acid (150 mL) and allowed to stir a room temperature for 4 h, producing a bright orange solution. The solid was filtered off, washed with H2O and dried. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent

1 which gave the title compound (0.85 g, 50%). H NMR (400 MHz, CDCl3) δ= 0.46 (s, 18H), 7.63-

7.65 (m, 4H), 8.60-8.62 (m, 4H).

9,10-bis(ethynyl)anthracene (24)

To a 250 mL round-bottom flask was added 9,10-bis(trimethylsilylethynyl)anthracene

(0.50 g, 1.35 mmol), K2CO3 (1.10 g, 8.00 mmol), CH2Cl2 (15 mL), and methanol (15 mL). The solution was stirred for 2 h at room temperature, quenched with 10% hydrochloric acid,

130 washed with H2O (3 x 30 mL), and extracted with CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

1 (0.28 g, 93%). H NMR (400 MHz, CDCl3) δ= 4.07 (s, 2H), 7.61-7.63 (m, 4H), 8.60-8.62 (m, 2H).

trans-Pd(PPh3)2(Cl)(corannulenyl) (25)

In a dry box with an argon atmosphere, to a pressure vessel was added iodocorannulene

(0.10 g, 0.26 mmol), tetrakis(triphenylphosphine)palladium (0.30 g, 0.26 mmol), and anhydrous

THF (15 mL). The pressure vessel was sealed, and the reaction mixture was stirred at room temperature for 24 hrs. The crude mixture was washed with 10% HCl (2 x 25 mL), water (2 x 25 mL), extracted with CH2Cl2 (3 x 25 mL) dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane: CH2Cl2 eluent which have the title compound (0.18 g, 79%). HRMS: calcd for

1 C56H39P2Pd+: 879.1581 found [M+] 878.9730. H NMR (400 MHz, CDCl3) δ = 7.86-7.84 (d, J = 8.0

Hz, 1H), 7.73-7.69 (m, 2H), 7.59-7.57 (d, J = 8.0 Hz, 1H), 7.52-7.49 (d, J = 12 Hz, 1H), 7.45-7.30

(m, 5H), 7.26-7.25 (m, 2H), 7.17-7.13 (m, 2H), 7.0-6.6 (m, 10H).

9-bromo-10-formalantharcene (26)

Procedure followed as prepared in the published method.69 To a oven-dried 500 mL round-bottom flask, under a flow of argon was added 9,10-dibromoanthracene (5.0 g, 14.9 mmol) and anhydrous THF (200 mL) and cooled to -100° C (CO2/diethylether) and allowed to

131 stir for 10 min. n-BuLi (11 mL, 16 mmol) was then added drop-wise over 0.25 h and allowed to stir for addition 0.5 h, producing an orange solution. Anhydrous DMF (2.5 mL) was then added and allowed to stir for 24 h, gradually warming to room temperature. The reaction was washed with H2O (50 mL), ammonium chloride solution (50 mL), H2O (2 x 50 mL), extracted with CH2Cl2

(3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified my column chromatography using a gradient cyclohexane : CH2Cl2 eluent

1 which gave the title compound (2.48 g, 60%). H NMR (400 MHz, CDCl3) δ= 7.64-7.70 (m, 4H),

8.66-8.68 (d, J = 8.0 Hz, 2H), 8.87-8.89 (d, J = 8.8 Hz, 2H), 11.49 (s, 1H).

9-bromo-10-ethynylanthracene (27)

Procedure modified as prepared in the published method.69 To a oven-dried 250 mL round-bottom flask, under a flow of argon was added PPh3 (2.30 g, 8.8 mmol) and anhydrous

CH2Cl2 (50 mL) and cooled to -15° C (CO2/ethylene glycol). To the stirred solution was added

CBr4 (2.94 g, 8.8 mmol) and let stir for 0.5 h. The solution was cooled to -70° C (CO2/Acetone) and to it was added a solution of 9-bromo-10-formalantharcene (1.0 g, 3.5 mmol), Et3N (0.80 mL, 5.6 mmol), in anhydrous CH2Cl2 (50 mL)and let stirred warming slowly to room temperature for 24 h. The crude mixture was washed with 10% HCl (2 x 25 mL), water (2 x 25 mL),extracted with CH2Cl2 (3 x 25 mL) dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound (0.95 g, 62%). The compound was then used quickly to the next step. To a oven-dried round-bottom flask was added n-BuLi (0.96

132 mL, 1.4 mmol), diisopropylamine (0.216 mL, 1.5 mmol) in anhydrous THF (15 mL). Allowed to stir at 0° C for 0.75 h producing LDA. The LDA solution was added to 9-bromo-10-(2,2- dibromovinyl)anthracene (product produced previously) (0.33 g, 0.77 mmol) in anhydrous THF

(30 mL) at -70° C (CO2/acetone) and allowed to stir for 1.5 h producing a dark green solution.

Reaction quenched with 10% aqueous hydrochloric acid, wash with H2O (2 x 25 mL), extracted with CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure.

The crude mixture was purified my column chromatography using a gradient cyclohexane :

1 CH2Cl2 eluent which gave the title compound (0.15 g, 79%). H NMR (400 MHz, CDCl3) δ= 4.08

(s, 1H), 7.63-7.67 (m, 4H), 8.57-8.66 (m, 4H).

9-bromo 10-(corannulenylethynyl)anthracene (28)

In a dry box with an argon atmosphere, to a pressure vessel was added 9-bromo-10- ethynylanthracene (0.125 g, 0.440 mmol), iodocorannulene (0.50 g, 1.33 mmol), tetrakis triphenylphosphine palladium (0) (0.063 g, 0.055 mmol), copper iodide (0.008 g, 0.044 mmol, triethylamine (10 mL) and anhydrous THF (10 mL). The pressure vessel was sealed, and the reaction mixture was stirred for 24 hrs at 70°C. The crude mixture was washed with 10% HCl (2 x 25 mL), water (2 x 25 mL),extracted with CH2Cl2 (3 x 25 mL) dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

(0.100 g, 43%). HRMS: calcd for C36H17Br: [M+] 528.0514, [M+2] 530.0500 found [M+]

1 528.0352, [M+2] 530.0448 H NMR (400 MHz, CDCl3) δ 8.89-8.86 (m, 2H), 8.64-8.62 (m, 2H),

133

8.34-8.31 (m, 2H), 7.99-7.96 (d, J = 12.0 Hz, 1H), 7.87-7.84 (m, 6H), 7.72-7.69 (m, 4H) 13C NMR

(CDCl3) δ = 136.2, 135.8, 135.8, 135.5, 135.4, 134.1, 133.2, 131.9, 131.5, 131.3, 131.2, 131.1,

130.8, 130.7, 130.4, 128.4, 128.0, 127.7, 127.5, 127.3, 127.2, 127.2, 127.1, 127.0, 126.7, 126.2,

126.0, 125.5, 124.6, 124.5, 124.0, 121.4, 119.1, 118.2, 100.4, 89.6.

9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29)

In a dry box with an argon atmosphere, to a pressure vessel was added 9-bromo 10-

(corannulenylethynyl)anthracene (0.05 g, 0.094 mmol), phenyl acetylene (0.03 mL, 0.28 mmol), tetrakis triphenylphosphine palladium (0) (0.015 g, 0.012 mmol), copper iodide (0.001 g, 0.009 mmol), triethylamine (5 mL) and anhydrous THF (10 mL). The pressure vessel was sealed, and the reaction mixture was stirred at 75°C for 24 hrs. The crude mixture was washed with 10%

HCl (25 mL),water (3 x 25 mL), extracted with CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified my column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

1 (0.02 g, 40%). HRMS: calcd for C44H22: 550.1722 found [M+} 550.1706 H NMR (400 MHz,

CDCl3) δ 8.92-8.90 (d J = 8.0 Hz, 2H), 8.77-8.75 (d J = 8.0 Hz, 2H), 8.42-8.38 (m, 2H), 8.08-8.05 (d,

13 J = 12.0 Hz, 1H), 7.95-7.84 (m, 6H), 7.84-7.73 (m, 6H), 7.55-7.50 (m, 3H) C NMR (CDCl3) δ =

136.5, 136.1, 136.0, 135.7, 135.6, 132.4, 132.3, 131.9, 131.9, 131.8, 131.7, 131.7, 131.4, 131.3,

131.1, 130.9, 130.6, 130.5, 130.0, 129.9, 128.8, 128.7, 128.6, 128.0, 127.9, 127.8, 127.7, 127.6,

127.5, 127.4, 127.3, 127.2, 127.0, 126.9, 126.3, 123.7, 121.8, 119.6, 119.2, 118.6, 102.9, 101.3,

90.6, 86.9.

134

9-(corannulenylethynyl)anthracene (30)

In a dry box with an argon atmosphere, to a pressure vessel was added 9- ethynylanthracene (0.18 g, 0.89 mmol), iodocorannulene (0.613 g, 1.63 mmol), tetrakis triphenylphosphine palladium (0) (0.21 g, 0.178 mmol), copper iodide (0.02 g, 0.089 mmol), triethylamine ( 10 mL), and anhydrous THF (20 mL). The pressure vessel was sealed, and the reaction mixture was stirred for 48 hrs at 40°C. The crude mixture was washed with 10% HCl (2 x 25 mL), water (2 x 25 mL),extracted with CH2Cl2 (3 x 25 mL) dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

1 (0.25 g, 63%). HRMS: calcd for C36H18: 450.1408 found [M+] 450.1225 H NMR (400 MHz, CDCl3)

δ 8.83-8.80 (m, 2H), 8.49 (s, 1H), 8.35-8.30 (m, 2H), 8.07-8.05 (d, J = 8.0 Hz, 2H), 7.96-7.94 (d, J =

13 8.0 Hz, 1 H), 7.85-7.82 (m, 6H), 7.69-7.65 (m, 2H), 7.57-7.54 (m, 2H) C NMR (CDCl3) δ = 136.2,

135.8, 135.8, 135.4, 135.4, 132.8, 131.3, 131.3, 131.2, 131.2, 131.1, 130.9, 130.5, 128.9, 128.4,

128.1, 128.1, 127.9, 127.8, 127.7, 127.6, 127.5, 127.5, 127.2, 127.2, 126.9, 126.8, 126.7, 126.2,

125.8, 123.5, 122.8, 121.8, 117.3, 99.2, 90.1.

9-(phenylethynyl)anthracene (31)

In a dry box with an argon atmosphere, to a pressure vessel was added 9- bromoanthracene (0.50 g, 2.0 mmol), phenylacetylene (0.65 mL, 6.0 mmol), Pd(PPh3)4 (0.28 g,

0.24 mmol), CuI (0.04 g, 0.20 mmol), Et3N (10 mL), and anhydrous THF (10 mL). The pressure vessel was sealed, and the reaction mixture was stirred at 50° C for 24 h. The crude mixture was washed with 10% aqueous hydrochloric acid (25 mL),water (3 x 25 mL), extracted with

135

CH2Cl2 (3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified my column chromatography using a gradient cyclohexane : CH2Cl2

1 eluent which gave the title compound (0.43 g, 85%). H NMR (400 MHz, CDCl3) δ= 7.41-7.52 (m,

5H), 7.56-7.60 (m, 2H), 7.76-7.78 (m, 2H), 7.99-8.01 (d, J = 8.0 Hz, 2H), 8.41 (s, 1H), 8.64-8.66 (d,

J = 8.0 Hz, 2H).

9,10-bis(phenylethynyl)anthracene (32)

To an oven-dried round-bottom flask, under a flow of argon was added phenyl acetylene (2.15 g, 21.12 mmol), n-BuLi (1.8 mL, 19.2 mmol) in anhydrous THF (40 mL). The reaction mixture was allowed to stir at 0° C for 0.75 h. Anthracenequinone (2.0 g, 9.6 mmol) was then added and solution was allowed to stir for 24 h at room temperature. Reaction was quenched with 10% hydrochloric acid, washed with H2O (3 x 30 mL), and extracted with CH2Cl2

(3 x 25 mL), dried with magnesium sulfate and evaporated under reduced pressure. To a 500 mL round-bottom flask, was added the crude product and ethanol (150 mL) at stirred at room temperature. To the solution was added SnCl2 · 2H2O ( 10 eq) in 50% aqueous acetic acid (150 mL) and allowed to stir a room temperature for 4 h. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

1 (2.18 g, 60%). H NMR (400 MHz, CDCl3) δ= 7.44-7.46 (m, 6H), 7.63-7.65 (m, 4H), 7.77-7.79 (m,

4H), 8.68-8.71 (m, 4H).

136

1-(anthracenylethynyl)-4-[(4-corannuleneylethynyl)1-ethynyl)benzene]bicylco[2.2.2]octane (33)

In a dry box, under an argon atmosphere to a pressure vessel was added 42 (0.015 g,

0.045 mmol), 4-bromo-1-(corannulenylethynyl)benzene (0.048 g, 0.112 mmol), Pd(PPh3)4 (0.012 g, 0.012 mmol), CuI (0.001 g, 0.0045 mmol), triethylamine (5 mL), and anhydrous THF (5 mL) and stirred at 60° C for 24 h. The reaction was quenched with 10% aqueous hydrochloric acid

(100 mL), washed with H2O (2 x 35 mL), dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified my column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title product (0.005, 17%).

1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene (34)

To a 100 mL round-bottom flask was added 50 (0.035 g, 0.043 mmol), TBAF (0.027 g,

0.087 mmol), and anhydrous THF (5 mL). The reaction was allowed to stir at room temperature for 1 h. The reaction was quenched with 10% aqueous ammonium chloride solution and extracted with CH2Cl2 (3 x 15 mL). The organic layers were combined, dried with magnesium sulfate and evaporated under reduced pressure. The crude mixture was purified by a plug of silica using CS2 as the eluent (0.025 g, 93%). In a dry box with an argon atmosphere, in a pressure vessel was added the crude product (0.025 g, 0.038 mmol), 9-iodoanthracene (0.07 g,

0.115 mmol), Pd(PPh3)4 (0.008 g, 0.007 mmol), CuI (0.0006 g, 0.0034 mmol), triethylamine (7 mL), and anhydrous THF (7 mL) and allowed to stir for 24 h at 65° C. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent, then by

1 preparative TLC using CS2 (0.014 g, 44%). H NMR (500 MHz, CDCl3) δ = 7.17-7.18 (m, 6H), 7.56-

137

7.59 (m, 2H), 7.65-7.68 (m, 2H), 7.77-7.85 (m, 9H), 7.88-7.91 (m, 6H), 8.06-8.16 (m, 6H), 8.55 (s,

13 1H), 8.92-8.93 (d, J = 8.8 Hz, 2H) C NMR (CDCl3) δ = 53.1, 54.0, 85.6, 89.8, 90.0, 92.8, 92.9,

94.8, 116.8, 121.1, 122.5, 122.7, 122.7, 122.9, 123.8, 125.9, 126.0, 126.0, 126.1, 126.1, 126.7,

127.2, 127.2, 127.5, 127.5, 127.6, 127.8, 128.3, 129.0, 130.4, 130.9, 131.0, 131.2, 131.3, 131.5,

132.0, 132.2, 132.3, 133.2, 135.3, 135.5, 135.8, 135.8, 136.2, 143.7, 144.0, 144.1.

1,4-dicarbethoxy-2,5-diketobicyclo[2.2.2]octane (35)

Modified procedures as prepared by the published method.58 In a dry box with an argon atmosphere, to a 1000 mL round bottom flask was added NaH (60% by weight) (20.0 g, 0.50 mol) and monoglyme (200 mL). To the stirred mixture was added t-butyl alcohol (5 g), and diethyl succinate (87 g, 0.50 mol). The temperature was raised to 60° C and allowed to stir for

24 h under argon. Monoglyme and ethanol were removed under reduced pressure producing a beige solid. To the solid was added 1,2-dibromoethane (50 mL) and monoglyme (250 mL) and was stirred at 85° C for 5-6 days. 1,2-dibromoethane and monoglyme were removed under reduced pressure. The crude product was washed with cyclohexane to remove oil impurities.

1 The crude solid was purified by a silica plug using CH2Cl2 as the eluent (15.5 g, 22%). H NMR

(400 MHz, CDCl3) δ = 1.26-1.32 (m, 6H), 2.12-2.15 (m, 2H), 2.49-2.52 (m, 2H), 2.70-2.75 (m, 2H),

3.05-3.18 (m, 2H), 4.23-4.29 (q, 4H).

138

Diethyl-2,5-bisdithianebicylco[2.2.2]octane-1,4-dicarboxylate (36)

Modified procedures as prepared by the published method.57 To a round bottom flask was added diketone-diester (35) (15.0 g, 0.05 mol), toluene (150 mL), 1,2-ethanedithiol (12.0 mL, 0.13 mol), and p-toluenesulfonic acid (0.75 g) as catalyst. The solution was allowed to stir under reflux using a Dean-Stark trap to remove H2O until no further H2O was produced (i.e. 24 h). Poured cooled solution into NaOH (2M, 1000 mL) and diluted with CH2Cl2 (200 mL). The organic layer was washed with H2O (3x50 mL), dried with magnesium sulfate and evaporated

1 under reduced pressure (18.0 g, 78%). H NMR (400 MHz, CDCl3) δ = 1.25-1.29 (m, 6H), 1.93-

1.97 (m, 2H), 2.51-2.53 (m, 2H), 2.84-2.88 (d, J = 16.0 Hz, 2H), 2.98-3.06 (m, 4H), 3.29-3.37 (m,

6H), 4.09-4.18 (m, 4H).

Diethyl-bicyclo[2.2.2]octane-1,4-dicarboxylate (37)

Modified procedures as prepared by the published method.61 To a 1000 mL round- bottom flask was added 36 (1.5g, 0.003 mol), 95% aqueous ethanol (200 mL), and Raney nickel

(22.5 g). CAUTION: Raney nickel is extremely flammable when dry. Allowed to stir under reflux for 48 h. The Raney nickel was filtered off (danger fire!) and quenched with 10% boric acid solution. The ethanol was removed under reduced pressure and the produce diluted with

CH2Cl2 (100 mL) and washed with H2O (3 x 40 mL), dried with magnesium sulfate, and

1 evaporated under reduced pressure (0.85g, 99%). H NMR (400 MHz, CDCl3) δ = 1.21-1.25 (t,

6H), 4.07-4.12 (q, 4H).

139

Bicyclo[2.2.2]octane-1,4-dimethanol (38)

Modified procedures as prepared by the published method.60 To a 100 mL round- bottom flask under a flow of argon was added (37) (0.55 g, 0.002 mol) and anhydrous diethylether (50 mL). DIBAL-H (9.02 mL, 0.011 mol) was then slowly added over 10 min and allowed to stir for an addition 2 h at room temperature. The reaction was quenched and the aluminum salts removed by the addition of aqueous sodium potassium tartrate (150 mL) and allowing it to stir for 5 h at room temperature. The organic product was extracted with diethylether (3 x 100 mL), dried with magnesium sulfate, and evaporated under reduced

1 pressure (0.35 g, 97%). H NMR (400 MHz, CDCl3) δ = 1.43 (s, 12H), 3.28 (s, 4H).

Bicyclo[2.2.2]octane-1,4-dicarboxaldehyde (39)

To a 100 mL round-bottom flask was added PCC (0.951 g, 4.4 mmol) and anhydrous

CH2Cl2 (10 mL) and stirred at room temperature for 10 min producing a yellow-orange solution.

To the stirred solution was added 38 (0.25 g, 1.5 mmol) in anhydrous CH2Cl2 (10 mL) and allowed to stir for an addition 2 h producing a dark brown solution. The reaction was diluted with diethylether (250 mL) and ran through a plug of silica using ether (300 mL) as the eluent.

The organic layer was evaporated under reduced pressure (using no heat) (0.24 g, 95%). 1H

NMR (400 MHz, CDCl3) δ = 1.72 (s, 12H), 9.47 (s, 2H).

140

1,4-bis(2,2-dibromovinyl)bicylo[2.2.2]octane (40)

Modified procedures as prepared by the published method.61 To a 100 mL round- bottom flask was added Zinc dust (0.385 g), CBr4 (1.93 g, 5.8 mmol), PPh3 (1.53 g, 5.8 mmol) and anhydrous CH2Cl2 (40 mL) and stirred under argon for 4 h. To the stirred suspension was added 39 (0.24 g, 1.4 mmol) and allowed to stir under argon at room temperature for additional 24 h. The reaction was diluted with 50 mL hexanes and ran through a plug of silica using hexane (100 mL) as the eluent. The organic layer was evaporated under reduced pressure

1 using no heat (0.36 g, 55%). H NMR (400 MHz, CDCl3) δ = 1.82 (s, 12H), 6.41 (s, 2H).

1,4-bis(ethynyl)benzobicyclo[2.2.2]octane (41)

Modified procedures as prepared by the published method.61 To a 100 mL round- bottom flask was added 40 (0.36 g, 0.75 mmol) and anhydrous THF (30 mL) and stirred, cooled to -78° C (CO2/acetone). To the stirred suspension was added n-BuLi (1.6 M) (2.9 mL, 4.5 mmol) slowly over 20 min and allowed to stir at -78° C for an additional 1 h, slowly warming to room temperature stirring for 1.5 h. The crude mixture was diluted with CH2Cl2, washed with H2O, dried with magnesium sulfate and evaporated under reduced pressure using no heat (0.12 g,

1 99%). H NMR (400 MHz, CDCl3) δ = 1.78 (s, 12H), 2.08 (s, 2H).

141

1-ethynyl-4-(anthracenylethynyl)bicyclo[2.2.2]octane (42)

In a dry box with an argon atmosphere, to a 100 mL round-bottom flask was added 41

(0.03 g, 0.19 mmol), 9-iodoanthracene (0.03 g, 0.095 mmol), Pd(PPh3)4 (0.21 g, 0.19 mmol), CuI

(0.003 g, 0.019 mmol), and piperidine (10 mL) and stirred at room temperature. The reaction was closely monitored by TLC (every 5 min) and after 50 min the reaction was quenched with

H2O and diluted with diethylether (30 mL). The organic layer was washed with H2O (5 x 25 mL), dried with magnesium sulfate, and evaporated under reduced pressure using no heat (0.015 g,

25%).

9,10-bis(trimethylsilylethynyl)triptycene (43)

Modified procedures as prepared by the published method.61 To a 500 mL, 3-necked round-bottom flask was added 9,10-bis(trimethylsilylethynyl)anthracene (0.50 g, 1.35 mmol), and anhydrous DME (25 mL). A condenser was added to the middle and stoppers to the ends of the 3-necked flask. The mixture was placed under a flow of argon and heated to 110° C. To a

25 mL flask was added isoamy nitrite (1 mL, 7.27 mmol) and anhydrous DME (7 mL). To a separate 25 mL flask was added anthranilic acid (0.75 g, 5.45 mmol) and anhydrous DME (7 mL).

Using a syringe pump, the two solutions were added at the same rate of 1.5 h. The reaction was allowed to reflux for an additional 4 h then heat reduced to 70° C for 24 h. The reaction was cooled and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient petroleum ether : cyclohexane eluent which gave the title

1 compound (0.12 g, 18%). H NMR (400 MHz, CDCl3) δ= 0.46 (s, 18H), 7.08-7.10 (m, 6H), 7.69-

13 7.72 (m, 6H) C NMR (CDCl3) δ = 0.4, 53.0, 98.1, 99.6, 122.2, 125.7, 143.3.

142

9,10-diethynyltriptycene (44)

To a 100 mL round-bottom flask was added 43 (0.09 g, 0.195 mmol), K2CO3 (0.11 g,

0.975 mmol), methanol (7 mL) and anhydrous THF (7 mL) and stirred at room temperature for 4 h. The reaction was diluted with CH2Cl2 and washed with H2O (3 x 30 mL), dried with magnesium sulfate, filtered and evaporated under reduced pressure (0.05 g, 90%). 1H NMR

13 (400 MHz, CDCl3) δ= 3.63 (s, 2H), 7.44-7.46 (m, 6H), 8.09-8.11 (m, 6H) C NMR (CDCl3) δ = 52.3,

78.0, 81.0, 122.2, 125.9, 143.0.

1-ethynyl-4-(anthracenylethynyl)triptycene (45)

In a dry box with an argon atmosphere, to a 100 mL round-bottom flask was added 44

(0.012 g, 0.04 mmol), 9-iodoanthracene (0.011 g, 0.04 mmol), Pd(PPh3)4 (0.04 g, 0.04 mmol),

CuI (0.0008 g, 0.004 mmol), triethylamine (7 mL) and anhydrous THF (7 mL). The reaction was stirred at room temperature for 24 h. . The reaction was cooled and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound (0.005 g, 20 %).

9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthra-9,10diol (46)

To a 100 mL round-bottom flask under a flow of argon was added diethylether (25 mL),

TMS-acetylene (0.15 mL, 1.06 mmol), and TIPS-acetylene (0.238 mL, 1.06 mmol). To the stirred suspension was added n-BuLi (1.6 M) (1.2 mL, 1.92 mmol) and allowed to stir for an additional

1.5 hr. Anthracenequinone (0.2 g, 0.96 mmol) was then added and allowed to stir for 24 h at room temperature. The reaction was quenched by 10% aqueous hydrochloric acid addition and

143 diluted with CH2Cl2, washed with H2O (3 x 30 mL), dried with magnesium sulfate, and evaporated under reduced pressure. The crude mixture was used in the next step without purification or characterization.

9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene (47)

To a 500 mL round-bottom flask was added crude 46 from the previous step, excess

SnCl2 ·2H2O in 50% aqueous acetic acid (400 mL) and allowed to stir at 50° C for 3 h producing an orange solution. The solid was filtered and dissolved in CH2Cl2 and washed with H2O (3 x 30

L), dried with magnesium sulfate, evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave a statistical ratio of products (0.26 g, 60%). The three products were then separated further by column chromatography using a gradient petroleum ether : cyclohexane eluent which gave the

1 title compound (0.1 g, 25%). H NMR (400 MHz, CDCl3) δ= 0.43 (s, 9H), 1.26-1.27 (m, 21H),

13 7.59-7.61 (m, 4H), 8.56-8.64 (m, 4H) C NMR (CDCl3) δ = 0.3, 11.6, 19.0, 101.7, 103.4, 105.0,

108.1, 118.4, 119.0, 126.9, 126.9, 127.3, 132.4, 132.5.

9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)triptycene (48)

Modified procedures as prepared by the published method.61 To a 500 mL, 3-necked round-bottom flask was added 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene

(0.08 g, 0.18 mmol), and anhydrous DME (20 mL). A condenser was added to the middle and stoppers to the ends of the 3-necked flask. The mixture was placed under a flow of argon and heated to 110° C. To a 25 mL flask was added isoamy nitrite (0.24 mL, 1.76 mmol) and

144 anhydrous DME (5 mL). To a separate 25 mL flask was added anthranilic acid (0.193 g, 1.41 mmol) and anhydrous DME (5 mL). Using a syringe pump, the two solutions were added at the same rate of 1.5 h. The reaction was allowed to reflux for an additional 4 h then heat reduced to 70° C for 24 h. The reaction was cooled and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient petroleum ether :

1 cyclohexane eluent which gave the title compound (0.023 g, 25%). H NMR (400 MHz, CDCl3)

13 δ= 0.46 (s, 9H), 1.29-1.30 (m, 21H), 7.08-7.10 (m, 6H), 7.70-7.78 (m, 6H) C NMR (CDCl3) δ =

0.4, 11.5, 18.9, 53.0, 53.4, 94.0, 98.1, 99.6, 101.2, 122.2, 122.3, 125.7, 125.7, 143.3, 143.5.

9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49)

To a round-bottom flask was added 48 (0.20 g, 0.38 mmol), K2CO3 (0.15 g, 1.1 mmol), methanol (7 mL), and CH2Cl2 (7 mL) and allowed to stir for 24 h. The reaction was washed with

0.011 mmol), triethylamine (7 mL), and anhydrous THF (7 mL) and allowed to stir at 65° C for 24 h. The reaction was quenched with 10% aqueous hydrochloric acid (250 mL), diluted with

CH2Cl2 (25 mL), washed with H2O (3 x 25 mL), dried with magnesium sulfate, and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a

1 gradient cyclohexane : CH2Cl2 eluent which gave the title compound (0.02 g, 25%). H NMR

(400 MHz, CDCl3) δ= 1.33-1.34 (m, 21H), 7.16-7.18 (m, 6H), 7.57-7.61 (m, 2H), 7.67-7.70 (m, 2H),

145

7.86-7.88 (m, 3H), 8.06-8.08 (m, 3H), 8.11-8.14, (d, J = 8.8 Hz, 2H), 8.58 (s, 1H), 8.93-8.95 (d, J =

13 8.8 Hz, 2H) C NMR (CDCl3) δ = 11.5, 18.9, 53.6, 54.0, 89.7, 94.3, 94.9, 101.4, 116.8, 122.5,

122.6, 125.8, 125.9, 126.7, 127.2, 128.3, 129.0, 131.3, 133.2, 143.7, 143.9.

9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10-(triisoproylsilylethynyl)triptycene (50)

To a round-bottom flask was added 48 (0.20 g, 0.38 mmol), K2CO3 (0.15 g, 1.1 mmol), methanol (7 mL), and CH2Cl2 (7 mL) and allowed to stir for 24 h. The reaction was washed with

10% hydrochloric acid (20 mL), diluted with CH2Cl2 (20 mL) washed with H2O (3 x 20 mL), dried with magnesium sulfate and evaporated under reduced pressure (0.15 g, 88%). To a pressure vessel, in a dry box under an argon atmosphere was added the crude product (0.05 g, 0.11 mmol), 4-bromo-1-(corannulenylethynyl)benzene (0.09 g, 0.22 mmol), Pd(PPh3)4 (0.032 g, 0.27 mmol), CuI (0.002 g, 0.011 mmol), triethylamine (7 mL), and anhydrous THF (7 mL) and allowed to stir at 70° C for 24 h. The reaction was quenched with 10% aqueous hydrochloric acid (250 mL), diluted with CH2Cl2 (25 mL), washed with H2O (3 x 25 mL), dried with magnesium sulfate, and evaporated under reduced pressure. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent which gave the title compound

1 (0.09 g, 50%). H NMR (400 MHz, CDCl3) δ= 1.31-1.32 (m, 21H), 7.10-7.14 (m, 6H), 7.77-7.92 (m,

13 17H), 8.11 (s, 1H), 8.15-8.17 (d, J = 8.8 Hz, 1H) C NMR (CDCl3) δ = 11.5, 18.9, 52.9, 53.5, 85.6,

89.9, 92.8, 92.8, 94.2, 101.2, 121.1, 122.1, 122.3, 122.4, 122.5, 122.9, 123.8, 125.8, 125.9,

126.0, 126.1, 126.7, 127.2, 127.5, 127.5, 127.6, 127.7, 130.3, 130.9, 131.0, 131.2, 131.3, 131.5,

131.9, 132.5, 135.3, 135.5, 135.7, 135.8, 136.2, 143.6.

146

9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10-[(9-corannulenylethynyl-10- ethynyl)anthracene]triptycene (51)

To a 100 mL round-bottom flask was added 50 (0.035 g, 0.043 mmol), TBAF (0.027 g,

(corannulenylethynyl)anthracene (0.048 g, 0.091 mmol), Pd(PPh3)4 (0.008 g, 0.007 mmol), CuI

(0.0006 g, 0.0034 mmol), triethylamine (7 mL), and anhydrous THF (7 mL) and allowed to stir for

24 h at 70° C. The crude mixture was purified by column chromatography using a gradient cyclohexane : CH2Cl2 eluent, then by preparative TLC using CS2 (0.007 g, 22%).

6,13-bis(phenylethynyl)pentacene (52)

To an oven-dried flask was added toluene (200 mL), and phenylacetylene (0.39 mL, 3.5 mmol), placed under a flow of argon and cooled to -18° C (ethylene glycole/CO2). To the stirred suspension was added n-BuLi (1.6 M) (2.02 mL, 3.2 mmol), and allowed to stir for an additional

1 h. To the stirred suspension was added 6,13-pentacenequinone (0.50g, 1.6 mmol) and allowed to stir overnight, slowly warming to room temperature. The reaction was washed with saturated aqueous ammonium chloride solution, H2O (2 x 30), dried with magnesium sulfate and evaporated under reduced pressure. The crude diol was dissolved in dioxane (150 mL) and allowed to stir. To a 50% aqueous solution of acetic acid was added a large excess of SnCl2 and

147 added to the original solution resulting in a greenish/yellow colored solution. The solution was stirred overnight covered, and filtered giving a greenish/yellow solid. The solid was washed

1 with H2O, dioxane, and cold chloroform producing the title compound as a blue solid. H NMR

(400 MHz, CDCl3) δ= 7.28-7.35 (m, 6H), 7.50-7.55 (m, 8H), 7.93-7.96 (m, 4H), 8.69 (s, 4H).

6,13-bis(trimethylsilylethynyl)penta-6,13-diol (53)

To an oven-dried flask was added anhydrous diethylether (40 mL) and TMS-acetylene

(2.1 mL, 14.93 mmol), cooled to 0° C (ice bath) and placed under a flow of argon. To the stirred suspension was added n-BuLi (1.6 M) (9.3 mL, 13.5 mmol) and allowed to stir for 1 h. To the stirred solution was added pentacenequinone (2.0 g, 6.5 mmol) and allowed to stir overnight slowly warming to room temperature. The reaction was washed with saturated aqueous ammonium chloride solution, H2O (2 x 30), dried with magnesium sulfate and evaporated under

1 reduced pressure to give the title compound (3.27 g, 87%). H NMR (400 MHz, CDCl3) δ= 0.25

(s, 18H), 3.70 (s, 2H), 7.56-7.59 (m, 4H), 7.95-7.98 (m, 4H), 8.63 (s, 4H).

6,13-bis(trimethylsilylethynyl)-6,13-bis(t-butlydimethylsilyl) -pentacene (54)

To an oven-dried round bottom flask was added 53 (1.0 g, 1.98 mmol) and anhydrous

DMF (25 mL). To the stirred suspension was added TBDMS-Cl (0.89 g, 5.95 mmol) and imidazole (0.81 g, 11.88 mmol), placed under a flow of argon and let stir for 24 h. The solution was diluted with diethylether (200 mL), quenched with 10% aqueous hydrochloric acid (120 mL), and washed with H2O (2 x 200 mL), dried with magnesium sulfate and evaporated under

148 reduced pressure yielding a dark black oil (1.40 g, 96%). 0.11 (s, 12H), 0.26 (s, 18H), 0.91-0.94

(m, 18H), 7.54-7.56 (m, 4H), 7.92-7.94 (m, 4H), 8.63 (s, 4H).

6,13-diethynyl-6,13-ditetahydropyran-pentacene (55)

To an oven-dried round bottom flask was added 54 (0.40 g, 0.59 mmol), K2CO3 (0.50 g,

3.57 mmol), methanol (15 mL) and anhydrous CH2Cl2 (15 mL) and stirred at room temperature for 2.5 h. The mixture was washed with H2O (2 x 30 mL), dried with magnesium sulfate, and evaporated under reduced pressure yielding the title compound (0.30 g, 98%).

Acetylcorannulene (58)

To a stirred solution of aluminum chloride (0.16 g, 1.2 mmol) in anhydrous methylene chloride (25 mL) under a flow of argon, was added acetyl chloride (0.043 mL, 0.60 mmol) at 0°C.

The solution was allowed to stir for 20 min. Corannulene (0.30 g, 1.2 mmol) was then added and allowed to stir at 0°C for an additional 1 h. The solution was then allowed to warm to room temperature and stirred for 20 h. The crude mixture was extracted with methylene chloride, dried with MgSO4, filtered, evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent to provide a yellow solid (0.28 g,

1 80% yield). H NMR (400 MHz, CDCl3) δ = 2.81 (s, 3H), 7.71-7.81 (m, 7H), 8.41 (s, 1H), 8.55 (d, J =

13 8.8 Hz, 1H) ppm. C NMR (CDCl3) δ = 28.5, 128.0, 127.0, 127.1, 127.4, 127.5, 128.1, 128.2,

128.3, 128.4, 128.7, 130.7 (2C), 132.0, 132.2, 134.9, 135.1, 135.7, 136.2, 136.4, 137.5, 199.6 ppm.

149

Benzoylcorannulene (59)

To a stirred solution of aluminum chloride (0.16 g, 1.2 mmol) in anhydrous methylene chloride (25 mL) under a flow of argon, was added benzoyl chloride (0.07 mL, 0.60 mmol) at

0°C. The solution was allowed to stir for 20 min. Corannulene (0.30 g, 1.2 mmol) was then added and allowed to stir at 0°C for an additional 1 h. The solution was then allowed to warm to room temperature and stirred for 20 h. The crude mixture was extracted with methylene chloride, dried with MgSO4, filtered, evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent to provide a yellow solid

1 (0.33 g, 78%). H NMR (400 MHz, CDCl3) δ = 7.56 (t, J= 7.6 Hz, 2H), 7.68 (t, J= 7.6 Hz, 1H), 7.83-

7.90 (m, 7H), 8.01 (dd, J= 7.6, 1.6 Hz, 2H), 8.07 (d, J= 8.8, 1H), 8.22 (s, 1H) ppm. 13C NMR (CDCl3)

δ= 127.1, 127.1, 127.2, 127.5, 127.7, 127.9, 128.1, 128.4, 128.8, 129.0, 130.2, 130.4, 130.9,

131.0, 131.9, 132.1, 132.8, 135.2, 135.5, 135.6, 136.4, 136.6, 137.1, 138.9, 196.8 ppm.

Corannulene aldehyde (60)

To a solution of corannulene (0.10 g, 0.4 mmol) in anhydrous methylene chloride (20 mL) under a blanket of nitrogen was added α,α-dichloromethyl methyl ether (0.46 g, 3.2 mmol) and titanium tetrachloride (0.41 g, 2.0 mmol). The mixture was stirred at room temperature for a period of 2 h. Ice was then added and allowed to stir for an additional 20 min. The crude mixture was extracted with methylene chloride, dried with MgSO4, filtered, evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane–CH2Cl2

1 eluent to provide a yellow solid (0.10 g, 90%). H NMR (400 MHz, CDCl3) δ = 7.81-7.93 (m, 7H),

150

13 8.39 (s, 1H), 8.69 (d, J= 8.0 Hz, 1H), 10.39 (s, 1H) C NMR (CDCl3) δ = 193.3, 139.1, 138.1, 136.5,

136.0, 135.2, 135.1, 134.9, 132.4, 131.2, 130.8, 128.9, 128.9, 128.8, 128.7, 127.8, 127.6, 127.6,

127.3, 127.2, 127.0

1-corannulenyl-1-propene (61)

To a stirred solution of ethyltriphenylphosphonium bromide (1.46 g, 3.9 mmol) in anhydrous THF (30 mL) under a flow of argon was added n-butyl lithium (0.20 g, 3.1 mmol).

The solution was allowed to stir for 30 min at room temperature. Corannulene aldehyde (0.11 g, 0.39 mmol) in anhydrous THF (30 mL) was then added. The solution was then allowed to stir for an additional 24 h at room temperature. The crude mixture was extracted with methylene chloride, dried with MgSO4, filtered, evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent to provide a yellow solid

1 (0.04 g, 35%). H NMR (400 MHz, CDCl3) δ = 2.14 (dd, J= 6.8 Hz, 1.2 Hz, 3H), 6.59-6.64 (m, 1H)

13 7.03 (d, J= 15.6 Hz, 1H), 7.72-7.83 (m, 7H), 8.05 (d, J= 8.8 Hz, 1H) C NMR (CDCl3) δ = 138.1,

136.2, 135.9, 135.7, 135.6, 135.0, 131.1, 130.9, 130.6, 130.5, 130.4, 129.1, 128.9, 127.2, 127.2,

127.2, 127.1, 127.0, 127.0, 126.8, 126.8, 125.8, 123.3, 19.2

151

1-corannulenyl-3-phenylpropenone (62)

To a stirred solution of phenacyltriphenylphosphonium bromide (0.82 g, 1.8 mmol) in anhydrous THF (30 mL) under a flow of argon was added n-butyl lithium (0.09 g, 1.4 mmol).

The solution was allowed to stir for 30 min at room temperature. Corannulene aldehyde (0.05 g, 0.18 mmol) in anhydrous THF (30 mL) was then added. The solution was then allowed to stir for an additional 24 h at room temperature. The crude mixture was extracted with methylene chloride, dried with MgSO4, filtered, evaporated under reduced pressure and purified by column chromatography using a gradient cyclohexane–CH2Cl2 eluent to provide a yellow solid

1 (0.021 g, 30%). H NMR (400 MHz, CDCl3) δ = 7.56 (t, J= 7.2 Hz, 2H), 7.63 (t, J= 7.2 Hz, 1H), 7.80-

7.83 (m, 6H), 7.87 (d, J= 8.8 Hz, 1H), 7.98 (d, J= 15.6 Hz, 1H) 8.13-8.17 (m, 4H), 8.44 (d, J= 15.6

13 Hz, 1H) C NMR (CDCl3) δ = 190.2, 142.7, 138.3, 136.6, 136.5, 135.9, 135.7, 135.3, 134.9, 133.0,

131.5, 131.1, 131.0, 130.2, 128.9, 128.8, 128.7, 128.2, 128.0, 127.7, 127.7, 127.6, 127.3, 127.1,

127.1, 125.3, 125.3

152

CHAPTER 8

Spectra

Figure 68. 1H NMR of 2,7-dimethylnaphthalene (2).

153

Figure 69. 13C NMR of 2,7-dimethylnaphthalene (2).

154

Figure 70. 1H NMR of 3,8-dimethylacenaphthenequinone (3).

155

Figure 71. 13C NMR of 3,8-dimethylacenaphthenequinone (3).

156

Figure 72. 1H NMR of 1,6,7,10-tetramethylfluoranthene (4).

157

Figure 73. 13C NMR of 1,6,7,10-tetramethylfluoranthene (4).

158

Figure 74. 1H NMR of 1,6,7,10-tetrakis(dibromomethyl)fluoranthene (5).

159

Figure 75. 13C NMR of 1,6,7,10-tetrakis(dibromomethyl)fluoranthene (5).

160

Figure 76. 1H NMR of corannulene (7).

161

Figure 77. 13C NMR of corannulene (7).

162

Figure 78. 1H NMR of bromocorannulene (8).

163

Figure 79. 13C NMR of bromocorannulene (8).

164

Figure 80. 1H NMR of iodocorannulene (9).

165

Figure 81. 1H NMR of ethynylcorannulene (10).

166

Figure 82. 13C NMR of ethynylcorannulene (10).

167

Figure 83. 1H NMR of 1,2-Bis(corannulenylethynyl)benzene (11).

168

Figure 84. 13C NMR of 1,2-Bis(corannulenylethynyl)benzene (11).

169

Figure 85. MALDI-TOF of 1,2-Bis(corannulenylethynyl)benzene (11).

170

Figure 86. 1H NMR of 1,3- Bis(corannulenylethynyl)benzene (12).

171

Figure 87. 13C NMR of 1,3- Bis(corannulenylethynyl)benzene (12).

172

Figure 88. MALDI-TOF of 1,3- Bis(corannulenylethynyl)benzene (12).

173

Figure 89. 1H NMR of 1,4- Bis(corannulenylethynyl)benzene (13).

174

Figure 90. 13C NMR of 1,4- Bis(corannulenylethynyl)benzene (13).

175

Figure 91. MALDI-TOF of 1,4- Bis(corannulenylethynyl)benzene (13).

176

Figure 92. 1H NMR of (Corannulenylethynyl)benzene (14).

177

Figure 93. 13C NMR of (Corannulenylethynyl)benzene (14).

178

Figure 94. 1H NMR of 2-bromo-(corannulenylethynyl)benzene (15).

179

Figure 95. 13C NMR of 2-bromo-(corannulenylethynyl)benzene (15).

180

Figure 96. 1H NMR of 3-bromo-(corannulenylethynyl)benzene (16).

181

Figure 97. 13C NMR of 3-bromo-(corannulenylethynyl)benzene (16).

182

Figure 98. 1H NMR of 4-bromo-(corannulenylethynyl)benzene (17).

183

Figure 99. 13C NMR of 4-bromo-(corannulenylethynyl)benzene (17).

184

Figure 100. 1H NMR of 2-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (18).

185

Figure 101. 1H NMR of 3-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (19).

186

Figure 102. 1H NMR of 4-(trimethysilylethynyl)-1-(corannulenylethynyl)benzene (20).

187

Figure 103. 1H NMR of 9,10-Bis(corannulenylethynyl)anthracene (21).

188

Figure 104. 13C NMR of 9,10-Bis(corannulenylethynyl)anthracene (21).

189

Figure 105. MALDI-TOF of 9,10-Bis(corannulenylethynyl)anthracene (21).

190

Figure 106. 1H NMR of 9,10-bis(trimethylsilylethynyl)anthracene (23).

191

Figure 107. 1H NMR of 9,10-bis(ethynyl)anthracene (24).

192

1 Figure 108. H NMR of trans-Pd(PPh3)2(Cl)(corannulenyl) (25).

193

Figure 109. ESI-MS of trans-Pd(PPh3)2(Cl)(corannulenyl) (25).

194

Figure 110. 1H NMR of 9-bromo-10-formalantharcene (26).

195

Figure 111. 1H NMR of 9-bromo-10-ethynylanthracene (27).

196

Figure 112. 1H NMR of 9-bromo 10-(corannulenylethynyl)anthracene (28).

197

Figure 113. 13C NMR of 9-bromo 10-(corannulenylethynyl)anthracene (28).

198

Figure 114. MALDI-TOF of 9-bromo 10-(corannulenylethynyl)anthracene (28).

199

Figure 115. 1H NMR of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29).

200

Figure 116. 13C NMR of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29).

201

Figure 117. MALDI-TOF of 9-(phenylethynyl)-10-(corannulenylethynyl)anthracene (29).

202

Figure 118. 1H NMR of 9-(corannulenylethynyl)anthracene (30).

203

Figure 119. 13C NMR of 9-(corannulenylethynyl)anthracene (30).

204

Figure 120. MALDI-TOF of 9-(corannulenylethynyl)anthracene (30).

205

Figure 121. 1H NMR of 9-(phenylethynyl)anthracene (31).

206

Figure 122. 1H NMR of 9,10-bis(phenylethynyl)anthracene (32).

207

Figure 123. 1H NMR of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene

(34).

208

Figure 124. 13C NMR of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene

(34).

209

Figure 125. MALDI-TOF of 1-(anthracenylethynyl)-4-(4-corannuleneylethynyl)ethynyltriptycene

(34).

210

Figure 126. 1H NMR of 1,4-dicarbethoxy-2,5-diketobicyclo[2.2.2]octane (35).

211

Figure 127. 1H NMR of diethyl-2,5-bisdithianebicylco[2.2.2]octane-1,4-dicarboxylate (36).

212

Figure 128. 1H NMR of diethyl-bicyclo[2.2.2]octane-1,4-dicarboxylate (37).

213

Figure 129. 1H NMR of bicyclo[2.2.2]octane-1,4-dimethanol (38).

214

Figure 130. 1H NMR of bicyclo[2.2.2]octane-1,4-dicarboxaldehyde (39).

215

Figure 131. 1H NMR of 1,4-bis(2,2-dibromovinyl)bicylo[2.2.2]octane (40).

216

Figure 132. 1H NMR of 1,4-bis(ethynyl)benzobicyclo[2.2.2]octane (41).

217

Figure 133. 1H NMR of 9,10-bis(trimethylsilylethynyl)triptycene (43).

218

Figure 134. 13C NMR of 9,10-bis(trimethylsilylethynyl)triptycene (43).

219

Figure 135. 1H NMR of 9,10-diethynyltriptycene (44).

220

Figure 136. 13C NMR of 9,10-diethynyltriptycene (44).

221

Figure 137. 1H NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene (47).

222

Figure 138. 13C NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)anthracene (47).

223

Figure 139. 1H NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)triptycene (48).

224

Figure 140. 13C NMR of 9 -(trimethylsilylethynyl)-10-(triisoproylsilylethynyl)triptycene (48).

225

Figure 141. 1H NMR of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49).

226

Figure 142. 13C NMR of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49).

227

Figure 143. MALDI-TOF of 9-(anthracenylethynyl)-10-(triisoproylsilylethynyl)triptycene (49).

228

Figure 144. 1H NMR of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10-

(triisoproylsilylethynyl)triptycene (50).

229

Figure 145. 13C NMR of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10-

(triisoproylsilylethynyl)triptycene (50).

230

Figure 146. MALDI-TOF of 9-[(4-corannuleneylethynyl-1-ethynyl)benzene]-10-

(triisoproylsilylethynyl)triptycene (50).

231

Figure 147. 1H NMR of 6,13-bis(phenylethynyl)pentacene (52).

232

Figure 148. 1H NMR of 6,13-bis(trimethylsilylethynyl)penta-6,13-diol (53).

233

Figure 149. 1H NMR of 6,13-bis(trimethylsilylethynyl)-6,13-bis(t-butlydimethylsilyl) -pentacene (54).

234

Figure 150. 1H NMR of acetylcorannulene (58).

235

Figure 151. 13C NMR of acetylcorannulene (58).

236

Figure 152. 1H NMR of benzoylcorannulene (59).

237

Figure 153. 13C NMR of benzoylcorannulene (59).

238

Figure 154. 1H NMR of corannulene aldehyde (60).

239

Figure 155. 13C NMR of corannulene aldehyde (60).

240

Figure 156. 1H NMR of 1-corannulenyl-1-propene (61).

241

Figure 157. 13C NMR of 1-corannulenyl-1-propene (61).

242

Figure 158. 1H NMR of 1-corannulenyl-3-phenylpropenone (62).

243

Figure 159. 13C NMR of 1-corannulenyl-3-phenylpropenone (62).

244

APPENDIX A

REFERENCES

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